Terminal, base station, cell access method, and data transmission method for reconfiguring a wireless connection to communicate with a secondary cell

ABSTRACT

A cell access method includes determining, by a terminal in communication with a first cell, to communicate with a second cell, establishing a wireless connection by which the terminal communicates with the second cell in response to the determining to communicate with the second cell, accessing the second cell on the wireless connection by the terminal, and receiving, by the terminal, a reconfiguration message sent by a first base station of the first cell. The reconfiguration message is sent by the first base station to the terminal. The method further includes reconfiguring the wireless connection according to the reconfiguration message, and communicating with the second cell on the reconfigured wireless connection.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is a continuation of International Application No.PCT/CN2016/087764, filed on Jun. 29, 2016, which claims priority toChinese Patent Application No. 201510374668.7, filed on Jun. 30, 2015.The disclosures of the aforementioned applications are herebyincorporated by reference in their entireties.

TECHNICAL FIELD

The present invention relates to wireless communications technologies,and in particular, to a terminal, a base station, a cell access method,and a data transmission method.

BACKGROUND

In a wireless communications system such as a Long Term Evolution (LTEfor short) system, a terminal is usually in two states: a radio resourcecontrol (Radio Resource Control, RRC) connected mode and an idle mode.Mobility of the terminal in both the two states is controlled by anetwork device such as a base station in the LTE system.

When the terminal is in the RRC connected mode and moves between cells,the network device determines whether the terminal needs to be handedover to a new cell, makes preparations for performing cell handoverbetween a source cell from which the terminal is handed over and atarget cell to which the terminal is handed over, and then instructs theterminal to access the target cell.

As shown in FIG. 1, a source base station sends a measurementconfiguration message to a terminal, and controls the terminal toperform wireless measurement on a source cell and a neighboring cell. Ina process in which the terminal moves from the source cell to a targetcell, when a condition indicated by the measurement configurationmessage is met, the terminal sends a measurement report to the sourcebase station. The source base station performs handover decision, sendsa handover request to a target base station of the target cell; andafter receiving a handover request acknowledgement from the target basestation, sends a handover command to the terminal, so as to instruct theterminal to be handed over from the source cell to the target cell.

In the RRC connected mode, the terminal cannot initiate a new RRCconnection establishment process to access a new cell. Instead, thenetwork device such as a base station or a core network device such as amobility management entity (Mobility Management Entity, MME) needs todetermine whether a new cell needs to be added for the terminal, so asto improve a maximum peak rate of the terminal.

In the idle mode, if the terminal needs to enter the RRC connected modeto perform data transmission, the terminal can access only a cell onwhich the terminal currently camps, and cannot access another cell.

When the terminal is in the idle mode and moves between cells, theterminal determines, according to a cell reselection rule in the cell onwhich the terminal currently camps and a cell reselection rule providedby the last cell after the terminal enters the RRC connected mode,whether to perform cell reselection, and which cell is to be reselected.These cell reselection rules are also specified by the network device.The terminal strictly performs cell reselection according to the cellreselection rule specified by the network device.

In conclusion, in a current wireless communications system such as theLTE system, both RRC state transition and mobility management of theterminal, for example, a cell handover process, a cell reselectionprocess, and a cell access process, need to be performed under thecontrol of the network device. The terminal strictly performs anoperation according to an instruction of the network device.

In the foregoing manner in which the network device strictly controlsthe terminal, although it is convenient to centrally manage the terminalby the network device, network implementation is complex, and deploymentand maintenance are not easy to perform.

SUMMARY

In view of this, embodiments of the present invention provide aterminal, a base station, and a cell access method, so as to enable theterminal to autonomously access a cell, and resolve the foregoingproblem where, because a network device strictly controls the terminal,network implementation is complex, and deployment and maintenance arenot easy to perform.

According to a first aspect, an embodiment of the present inventionprovides a terminal, where the terminal communicates with a first cell.The terminal includes a transceiver module, configured to when theterminal needs to communicate with a second cell, send a first celladdition request message to a first base station of the first cell,where the first cell addition request message is used to request thefirst base station to add the second cell as a cell communicating withthe terminal and a processing module, configured to, after receiving, byusing the transceiver module, a configuration message that is sent bythe first base station and is used to configure a wireless connection bywhich the terminal communicates with the second cell, configure,according to the configuration message, the wireless connection by whichthe terminal communicates with the second cell, and control the terminalto access the second cell by using the configured wireless connection bywhich the terminal communicates with the second cell.

With reference to the first aspect, in a first possible implementation,the processing module is specifically configured to obtain, from theconfiguration message, a wireless connection parameter that is used toconfigure the wireless connection by which the terminal communicateswith the second cell, and configure, according to the obtained wirelessconnection parameter, the wireless connection by which the terminalcommunicates with the second cell.

With reference to the first aspect or the first possible implementationof the first aspect, in a second possible implementation, thetransceiver module is further configured to after the processing moduleconfigures, according to the configuration message, the wirelessconnection by which the terminal communicates with the second cell, andbefore the processing module controls the terminal to access the secondcell, send a first configuration complete message to the first basestation, so as to indicate to the first base station that the terminalhas completed, according to the configuration message, configuration ofthe wireless connection by which the terminal communicates with thesecond cell.

With reference to the first aspect, or the first or the second possibleimplementation of the first aspect, in a third possible implementation,the processing module is further configured to before the transceivermodule sends the first cell addition request message, measure a wirelesssignal transmitted in the second cell, and determine, according to ameasurement result of the measuring, that the second cell is available.

With reference to the third possible implementation of the first aspect,in a fourth possible implementation, the transceiver module is furtherconfigured to before the processing module measures the wireless signaltransmitted in the second cell, receive a measurement configurationmessage sent by the first base station, where the measurementconfiguration message includes cell identity information of the secondcell, and information about a decision condition used to determinewhether the second cell is available. The processing module isspecifically configured to measure, according to the cell identityinformation of the second cell that is included in the measurementconfiguration message, the wireless signal transmitted in the secondcell, and when the measurement result of the measuring meets thedecision condition, determine that the second cell is available.

With reference to the third possible implementation of the first aspect,in a fifth possible implementation, the transceiver module is furtherconfigured to, before the processing module measures the wireless signaltransmitted in the second cell, receive a measurement configurationmessage sent by the first base station, where the measurementconfiguration message includes frequency information of the second cell,and information about a decision condition used to determine whether thesecond cell is available. The processing module is specificallyconfigured to measure, according to the frequency information of thesecond cell that is included in the measurement configuration message,the wireless signal transmitted in the second cell, and when themeasurement result of the measuring meets the decision condition,determine that the second cell is available.

With reference to any one of the third to the fifth possibleimplementations of the first aspect, in a sixth possible implementation,the transceiver module is further configured to, before the processingmodule measures the wireless signal transmitted in the second cell,receive a first indication message sent by the first base station or asecond base station of the second cell. The processing module is furtherconfigured to determine, according to the first indication message, thatthe second cell may be added as a cell communicating with the terminal,where the first indication message is used to indicate that the secondcell may provide communication for a same terminal together with thefirst cell.

With reference to any one of the first aspect, or the first to the sixthpossible implementations of the first aspect, in a seventh possibleimplementation, the first base station is a macro base station or asmall node, or the first base station includes an access node of thefirst cell and a control plane anchor corresponding to the access node,where the access node keeps a wireless connection to the terminal, thecontrol plane anchor is configured to control the terminal to establisha wireless connection to the access node, and enable, by exchanginginformation with a second server, the second server to perform userinformation management on the terminal, and the second server isconfigured to perform user information management on the terminal, andthe second base station of the second cell is a small node, a macro basestation, or a Wireless Fidelity WiFi access point AP.

According to a second aspect, an embodiment of the present inventionprovides a first base station, including a transceiver module,configured to receive a first cell addition request message sent by aterminal communicating with a first cell of the first base station,where the first cell addition request message is used to request thefirst base station to add a second cell as a cell communicating with theterminal, and a processing module, configured to control the transceivermodule to send, to the terminal, a configuration message that is used toconfigure a wireless connection by which the terminal communicates withthe second cell, so as to instruct the terminal to configure, accordingto the configuration message, the wireless connection by which theterminal communicates with the second cell, and access the second cell.

With reference to the second aspect, in a first possible implementation,the transceiver module is further configured to, after receiving thefirst cell addition request message, and before sending, to theterminal, the configuration message that is used to configure thewireless connection by which the terminal communicates with the secondcell, send a second cell addition request message to a second basestation of the second cell, so as to request to add the second cell as acell communicating with the terminal, and the processing module isspecifically configured to control the transceiver module to receive acell addition request acknowledgement message sent by the second basestation in response to the second cell addition request message, obtain,from the cell addition request acknowledgement message, a wirelessconnection parameter that is used to configure the wireless connectionby which the terminal communicates with the second cell, and control thetransceiver module to send the configuration message to the terminal,where the configuration message carries the obtained wireless connectionparameter, so as to instruct the terminal to configure, according to thewireless connection parameter, the wireless connection by which theterminal communicates with the second cell, and access the second cell.

With reference to the first possible implementation of the secondaspect, in a second possible implementation, the processing module isfurther configured to after controlling the transceiver module to sendthe configuration message to the terminal, and after the transceivermodule receives a first configuration complete message sent by theterminal in response to the configuration message, control thetransceiver module to send a second configuration complete message tothe second base station, so as to indicate the second base station thatthe terminal has completed configuration of the wireless connection bywhich the terminal communicates with the second cell, where the firstconfiguration complete message is used to indicate the first basestation that the terminal has completed, according to the configurationmessage, configuration of the wireless connection by which the terminalcommunicates with the second cell.

With reference to the second aspect, or the first or the second possibleimplementation of the second aspect, in a third possible implementation,the processing module is further configured to, before the transceivermodule receives the first cell addition request message sent by theterminal, control the transceiver module to send a measurementconfiguration message to the terminal, where the measurementconfiguration message includes cell identity information of the secondcell, and information about a decision condition used to determinewhether the second cell is available, where the first cell additionrequest message is sent by the terminal to the first base station afterthe terminal measures the second cell according to the cell identityinformation of the second cell in the measurement configuration message,and a measurement result obtained by measuring the second cell meets thedecision condition.

With reference to the second aspect, or the first or the second possibleimplementation of the second aspect, in a fourth possibleimplementation, the processing module is further configured to beforethe transceiver module receives the first cell addition request messagesent by the terminal, control the transceiver module to send ameasurement configuration message to the terminal, where the measurementconfiguration message includes frequency information of the second cell,and information about a decision condition used to determine whether thesecond cell is available, where the first cell addition request messageis sent by the terminal to the first base station after the terminalmeasures the second cell according to the frequency information of thesecond cell in the measurement configuration message, and a measurementresult obtained by measuring the second cell meets the decisioncondition.

With reference to the third or the fourth possible implementation of thesecond aspect, in a fifth possible implementation, the processing moduleis further configured to before controlling the transceiver module tosend the measurement configuration message to the terminal, control thetransceiver module to send a first indication message to the terminal,so as to indicate the terminal, the second cell may providecommunication for a same terminal together with the first cell.

With reference to any one of the second aspect, or the first to thefifth possible implementations of the second aspect, in a sixth possibleimplementation, the first base station is a macro base station or asmall node, or the first base station includes a first node of the firstcell and a first control node configured to control the first node,where the first node is configured to process transmission between theterminal and the first control node, and the base station of the secondcell is a small node, a macro base station, or a Wireless Fidelity WiFiaccess point AP.

According to a third aspect, an embodiment of the present inventionprovides a cell access method, including when a terminal communicatingwith a first cell needs to communicate with a second cell, sending, bythe terminal, a first cell addition request message to a first basestation of the first cell, where the first cell addition request messageis used to request the first base station to add the second cell as acell communicating with the terminal, after receiving a configurationmessage that is sent by the first base station and is used to configurea wireless connection by which the terminal communicates with the secondcell, configuring, by the terminal according to the configurationmessage, the wireless connection by which the terminal communicates withthe second cell, and accessing, by the terminal, the second cell byusing the configured wireless connection by which the terminalcommunicates with the second cell.

With reference to the third aspect, in a first possible implementation,the configuring, by the terminal according to the configuration message,the wireless connection by which the terminal communicates with thesecond cell includes obtaining, by the terminal from the configurationmessage, a wireless connection parameter that is used to configure thewireless connection by which the terminal communicates with the secondcell, and configuring, by the terminal according to the obtainedwireless connection parameter, the wireless connection by which theterminal communicates with the second cell.

With reference to the third aspect or the first possible implementationof the third aspect, in a second possible implementation, after theterminal configures, according to the configuration message, thewireless connection by which the terminal communicates with the secondcell, and before the terminal accesses the second cell, the methodfurther includes sending, by the terminal, a first configurationcomplete message to the first base station, so as to indicate to thefirst base station that the terminal has completed, according to theconfiguration message, configuration of the wireless connection by whichthe terminal communicates with the second cell.

With reference to the third aspect, or the first or the second possibleimplementation of the third aspect, in a third possible implementation,before the terminal sends the first cell addition request message, themethod further includes measuring, by the terminal, a wireless signaltransmitted in the second cell, and determining, according to ameasurement result of the measuring, that the second cell is available.

With reference to the third possible implementation of the third aspect,in a fourth possible implementation, before the measuring, by theterminal, a wireless signal transmitted in the second cell, the methodfurther includes receiving, by the terminal, a measurement configurationmessage sent by the first base station, where the measurementconfiguration message includes cell identity information of the secondcell, and information about a decision condition used to determinewhether the second cell is available, and the measuring, by theterminal, a wireless signal transmitted in the second cell, anddetermining, according to a measurement result of the measuring, thatthe second cell is available includes measuring, by the terminalaccording to the cell identity information of the second cell that isincluded in the measurement configuration message, the wireless signaltransmitted in the second cell, and when the measurement result of themeasuring meets the decision condition, determining that the second cellis available.

With reference to the third possible implementation of the third aspect,in a fifth possible implementation, before the measuring, by theterminal, a wireless signal transmitted in the second cell, the methodfurther includes receiving, by the terminal, a measurement configurationmessage sent by the first base station, where the measurementconfiguration message includes frequency information of the second cell,and information about a decision condition used to determine whether thesecond cell is available, and the measuring, by the terminal, a wirelesssignal transmitted in the second cell, and determining, according to ameasurement result of the measuring, that the second cell is availableincludes measuring, by the terminal according to the frequencyinformation of the second cell that is included in the measurementconfiguration message, the wireless signal transmitted in the secondcell, and when the measurement result of the measuring meets thedecision condition, determining that the second cell is available.

With reference to any one of the third to the fifth possibleimplementations of the third aspect, in a sixth possible implementation,before the measuring, by the terminal, a wireless signal transmitted inthe second cell, the method further includes receiving, by the terminal,a first indication message sent by the first base station or a secondbase station of the second cell, and determining, by the terminalaccording to the first indication message, that the second cell may beadded as a cell communicating with the terminal, where the firstindication message is used to indicate that the second cell may providecommunication for a same terminal together with the first cell.

With reference to any one of the third aspect, or the first to the sixthpossible implementations of the third aspect, in a seventh possibleimplementation, the first base station is a macro base station or asmall node, or the first base station includes an access node of thefirst cell and a control plane anchor corresponding to the access node,where the access node keeps a wireless connection to the terminal, thecontrol plane anchor is configured to control the terminal to establisha wireless connection to the access node, and enable, by exchanginginformation with a second server, the second server to perform userinformation management on the terminal, and the second server isconfigured to perform user information management on the terminal, andthe second base station of the second cell is a small node, a macro basestation, or a Wireless Fidelity WiFi access point AP.

According to a fourth aspect, an embodiment of the present inventionprovides a cell access method, including receiving, by a first basestation of a first cell, a first cell addition request message sent by aterminal communicating with the first cell, where the first celladdition request message is used to request the first base station toadd a second cell as a cell communicating with the terminal, andsending, by the first base station to the terminal, a configurationmessage that is used to configure a wireless connection by which theterminal communicates with the second cell, so as to instruct theterminal to configure, according to the configuration message, thewireless connection by which the terminal communicates with the secondcell, and access the second cell.

With reference to the fourth aspect, in a first possible implementation,after the first base station receives the first cell addition requestmessage, and before the first base station sends, to the terminal, theconfiguration message that is used to configure the wireless connectionby which the terminal communicates with the second cell, the methodfurther includes sending, by the first base station, a second celladdition request message to a second base station of the second cell, soas to request to add the second cell as a cell communicating with theterminal, and the sending, by the first base station to the terminal, aconfiguration message that is used to configure a wireless connection bywhich the terminal communicates with the second cell, so as to instructthe terminal to configure, according to the configuration message, thewireless connection by which the terminal communicates with the secondcell, and access the second cell includes receiving, by the first basestation, a cell addition request acknowledgement message sent by thesecond base station in response to the second cell addition requestmessage, obtaining, by the first base station from the cell additionrequest acknowledgement message, a wireless connection parameter that isused to configure the wireless connection by which the terminalcommunicates with the second cell, and sending, by the first basestation, the configuration message to the terminal, where theconfiguration message carries the obtained wireless connectionparameter, so as to instruct the terminal to configure, according to thewireless connection parameter, the wireless connection by which theterminal communicates with the second cell, and access the second cell.

With reference to the first possible implementation of the fourthaspect, in a second possible implementation, after the first basestation sends the configuration message to the terminal, the methodfurther includes receiving, by the first base station, a firstconfiguration complete message sent by the terminal in response to theconfiguration message, where the first configuration complete message isused to indicate the first base station that the terminal has completed,according to the configuration message, configuration of the wirelessconnection by which the terminal communicates with the second cell, andafter receiving the first configuration complete message, sending, bythe first base station, a second configuration complete message to thesecond base station, so as to indicate the second base station that theterminal has completed configuration of the wireless connection by whichthe terminal communicates with the second cell.

With reference to the fourth aspect, or the first or the second possibleimplementation of the fourth aspect, in a third possible implementation,before the first base station receives the first cell addition requestmessage sent by the terminal, the method further includes sending, bythe first base station, a measurement configuration message to theterminal, where the measurement configuration message includes cellidentity information of the second cell, and information about adecision condition used to determine whether the second cell isavailable, where the first cell addition request message is sent by theterminal to the first base station after the terminal measures thesecond cell according to the cell identity information of the secondcell in the measurement configuration message, and a measurement resultobtained by measuring the second cell meets the decision condition.

With reference to the fourth aspect, or the first or the second possibleimplementation of the fourth aspect, in a fourth possibleimplementation, before the first base station receives the first celladdition request message sent by the terminal, the method furtherincludes sending, by the first base station, a measurement configurationmessage to the terminal, where the measurement configuration messageincludes frequency information of the second cell, and information abouta decision condition used to determine whether the second cell isavailable, where the first cell addition request message is sent by theterminal to the first base station after the terminal measures thesecond cell according to the frequency information of the second cell inthe measurement configuration message, and a measurement result obtainedby measuring the second cell meets the decision condition.

With reference to the third or the fourth possible implementation of thefourth aspect, in a fifth possible implementation, before the first basestation sends the measurement configuration message to the terminal, themethod further includes sending, by the first base station, a firstindication message to the terminal, so as to indicate the terminal thatthe second cell may provide communication for a same terminal togetherwith the first cell.

With reference to any one of the fourth aspect, or the first to thefifth possible implementations of the fourth aspect, in a sixth possibleimplementation, the first base station is a macro base station or asmall node, or the first base station includes a first node of the firstcell and a first control node configured to control the first node,where the first node is configured to process transmission between theterminal and the first control node, and the base station of the secondcell is a small node, a macro base station, or a Wireless Fidelity WiFiaccess point AP.

According to a fifth aspect, an embodiment of the present inventionprovides a terminal, where the terminal communicates with a first cell,and the terminal includes a processing module, configured to when theterminal needs to communicate with a second cell, initiate a connectionestablishment process, establish, by using the connection establishmentprocess, a wireless connection by which the terminal communicates withthe second cell, and control the terminal to access the second cell byusing the established wireless connection, and a transceiver module,configured to receive a reconfiguration message sent by a first basestation of the first cell, where the processing module is furtherconfigured to after the transceiver module receives the reconfigurationmessage, reconfigure the wireless connection according to thereconfiguration message, and control the terminal to communicate withthe second cell by using the reconfigured wireless connection, where thereconfiguration message is sent by the first base station to theterminal after the first base station determines, according to aterminal access indication message that is received from a second basestation of the second cell and is used to indicate that the terminalaccesses the second cell, that the terminal accesses the second cell,and after the first base station determines that the second base stationallows addition of the second cell as a cell communicating with theterminal.

With reference to the fifth aspect, in a first possible implementation,the processing module is further configured to after reconfiguring thewireless connection according to the reconfiguration message, and beforecontrolling the terminal to communicate with the second cell by usingthe reconfigured wireless connection, control the transceiver module tosend a reconfiguration complete message to the first base station, so asto indicate to the first base station that the terminal has completedreconfiguration of the wireless connection according to thereconfiguration message.

With reference to the fifth aspect or the first possible implementationof the fifth aspect, in a second possible implementation, the processingmodule is further configured to before controlling the terminal toestablish the wireless connection to the second cell, measure a wirelesssignal transmitted in the second cell, and determine, according to ameasurement result of the measuring, that the second cell is available.

With reference to the second possible implementation of the fifthaspect, in a third possible implementation, the transceiver module isfurther configured to before the processing module measures the wirelesssignal transmitted in the second cell, receive a measurementconfiguration message sent by the first base station, where themeasurement configuration message includes cell identity information ofthe second cell, and information about a decision condition used todetermine whether the second cell is available, and the processingmodule is specifically configured to measure, according to the cellidentity information of the second cell that is included in themeasurement configuration message, the wireless signal transmitted inthe second cell, and when the measurement result of the measuring meetsthe decision condition, determine that the second cell is available.

With reference to the second possible implementation of the fifthaspect, in a fourth possible implementation, the transceiver module isfurther configured to before the processing module measures the wirelesssignal transmitted in the second cell, receive a measurementconfiguration message sent by the first base station, where themeasurement configuration message includes frequency information of thesecond cell, and information about a decision condition used todetermine whether the second cell is available, and the processingmodule is specifically configured to measure, according to the frequencyinformation of the second cell that is included in the measurementconfiguration message, the wireless signal transmitted in the secondcell, and when the measurement result of the measuring meets thedecision condition, determine that the second cell is available.

With reference to any one of the second to the fourth possibleimplementations of the fifth aspect, in a fifth possible implementation,the transceiver module is further configured to before the processingmodule measures the wireless signal transmitted in the second cell,receive a first indication message sent by the second base station orthe first base station, and the processing module is further configuredto determine, according to the first indication message, that the secondcell may be added as a cell communicating with the terminal, where thefirst indication message is used to indicate that the second cell mayprovide communication for a same terminal together with the first cell.

With reference to any one of the fifth aspect, or the first to the fifthpossible implementations of the fifth aspect, in a sixth possibleimplementation, the first base station is a macro base station or asmall node, or the first base station includes a first node of the firstcell and a first control node configured to control the first node,where the first node is configured to process transmission between theterminal and the first control node, and the second base station is asmall node, a macro base station, or a Wireless Fidelity WiFi accesspoint AP.

According to a sixth aspect, an embodiment of the present inventionprovides a first base station, including a transceiver module,configured to receive a terminal access indication message that is sentby a second base station of a second cell and is used to indicate that aterminal communicating with a first cell of the first base stationaccesses the second cell, and a processing module, configured to afterthe transceiver module receives the terminal access indication message,and if determining that the second base station allows addition of thesecond cell as a cell communicating with the terminal, control thetransceiver module to send a reconfiguration message to the terminal, soas to instruct the terminal to reconfigure, according to thereconfiguration message, a wireless connection established when theterminal accesses the second cell, and communicate with the second cellby using the configured wireless connection.

With reference to the sixth aspect, in a first possible implementation,the terminal access indication message is further used to indicate thatthe second base station allows addition of the second cell as a cellcommunicating with the terminal, and the processing module isspecifically configured to after the transceiver module receives theterminal access indication message, determine that the second basestation allows addition of the second cell as a cell communicating withthe terminal.

With reference to the first possible implementation of the sixth aspect,in a second possible implementation, the terminal access indicationmessage carries a wireless connection parameter that is used toreconfigure the wireless connection, and the processing module isspecifically configured to add, to the reconfiguration message, thewireless connection parameter obtained from the terminal accessindication message, and send the reconfiguration message to the terminalby using the transceiver module, where the reconfiguration message isspecifically used to instruct the terminal to reconfigure the wirelessconnection according to the wireless connection parameter, andcommunicate with the second cell by using the configured wirelessconnection.

With reference to the sixth aspect, in a third possible implementation,the processing module is further configured to after the transceivermodule receives the terminal access indication message, control thetransceiver module to send a cell addition request message to the secondbase station, so as to request the second base station to add the secondcell as a cell communicating with the terminal, and the processingmodule is specifically configured to after the transceiver modulereceives a cell addition request acknowledgement message sent by thesecond base station in response to the cell addition request message,determine that the second base station allows addition of the secondcell as a cell communicating with the terminal.

With reference to the third possible implementation of the sixth aspect,in a fourth possible implementation, the cell addition requestacknowledgement message carries a wireless connection parameter that isused to reconfigure the wireless connection, and the processing moduleis specifically configured to add, to the reconfiguration message, thewireless connection parameter obtained from the cell addition requestacknowledgement message, and send the reconfiguration message to theterminal by using the transceiver module, where the reconfigurationmessage is specifically used to instruct the terminal to reconfigure thewireless connection according to the wireless connection parameter, andcommunicate with the second cell by using the configured wirelessconnection.

With reference to any one of the sixth aspect, or the first to thefourth possible implementations of the sixth aspect, in a fifth possibleimplementation, the transceiver module is further configured to aftersending the reconfiguration message to the terminal, receive areconfiguration complete message sent by the terminal in response to thereconfiguration message, and the processing module is further configuredto determine, according to the reconfiguration complete message, thatthe terminal has completed reconfiguration of the wireless connectionaccording to the reconfiguration message, and control the transceivermodule to send a cell addition complete message to the second basestation, so as to indicate the second base station that the terminal hascompleted reconfiguration of the wireless connection.

With reference to any one of the sixth aspect, or the first to the fifthpossible implementations of the sixth aspect, in a sixth possibleimplementation, the processing module is further configured to beforethe transceiver module receives the terminal access indication message,control the transceiver module to send a measurement configurationmessage to the terminal, where the measurement configuration messageincludes cell identity information of the second cell, and informationabout a decision condition used to determine whether the second cell isavailable, so as to instruct the terminal to measure, according to thecell identity information of the second cell that is included in themeasurement configuration message, a wireless signal transmitted in thesecond cell, and when a measurement result of the measuring meets thedecision condition, determine that the second cell is available.

With reference to any one of the sixth aspect, or the first to the fifthpossible implementations of the sixth aspect, in a seventh possibleimplementation, the processing module is further configured to beforethe transceiver module receives the terminal access indication message,control the transceiver module to send a measurement configurationmessage to the terminal, where the measurement configuration messageincludes frequency information of the second cell, and information abouta decision condition used to determine whether the second cell isavailable, so as to instruct the terminal to measure, according to thefrequency information of the second cell that is included in themeasurement configuration message, a wireless signal transmitted in thesecond cell, and when a measurement result of the measuring meets thedecision condition, determine that the second cell is available.

With reference to the sixth or the seventh possible implementation ofthe sixth aspect, in an eighth possible implementation, the processingmodule is further configured to before controlling the transceivermodule to send the measurement configuration message, control thetransceiver module to send a first indication message to the terminal,where the first indication message is used to indicate that the secondcell may provide communication for a same terminal together with thefirst cell.

With reference to any one of the sixth aspect, or the first to theeighth possible implementations of the sixth aspect, in a ninth possibleimplementation, the first base station is a macro base station or asmall node, or the first base station includes a first node of the firstcell and a first control node configured to control the first node,where the first node is configured to process transmission between theterminal and the first control node, and the second base station is asmall node, a macro base station, or a Wireless Fidelity WiFi accesspoint AP.

According to a seventh aspect, an embodiment of the present inventionprovides a second base station, including a processing module and atransceiver module, where the processing module is configured toestablish a wireless connection between a terminal and the second cellof the second base station in a connection establishment processinitiated by the terminal, and allow the terminal to access the secondcell by using the wireless connection, and the processing module isfurther configured to after the terminal accesses the second cell,control the transceiver module to send a terminal access indicationmessage to a first base station of a first cell communicating with theterminal, so as to indicate that the second cell needs to be added, forthe terminal, as a cell communicating with the terminal.

With reference to the seventh aspect, in a first possibleimplementation, the terminal access indication message is further usedto indicate that the second base station allows addition of the secondcell as a cell communicating with the terminal, and the processingmodule is specifically configured to add, to the terminal accessindication message, a wireless connection parameter that is used toreconfigure the wireless connection, so as to instruct the first basestation to instruct the terminal to reconfigure the wireless connectionaccording to the wireless connection parameter.

With reference to the first possible implementation of the seventhaspect, in a second possible implementation, the transceiver module isfurther configured to after sending the terminal access indicationmessage to the first base station, receive a cell addition completemessage sent by the first base station, and the processing module isfurther configured to after the transceiver module receives the celladdition complete message, control the transceiver module to communicatewith the terminal by using the reconfigured wireless connection.

With reference to the seventh aspect, in a third possibleimplementation, the transceiver module is further configured to aftersending the terminal access indication message to the first basestation, receive a cell addition request message sent by the first basestation, where the cell addition request message is used to request thesecond base station to add the second cell as a cell communicating withthe terminal, and the processing module is further configured to controlthe transceiver module to send a cell addition request acknowledgementmessage to the first base station in response to the cell additionrequest message, so as to indicate that the second base station allowsaddition of the second cell as a cell communicating with the terminal,where the cell addition request acknowledgement message carries awireless connection parameter that is used to reconfigure the wirelessconnection, so as to instruct the first base station to instruct theterminal to reconfigure the wireless connection according to thewireless connection parameter.

With reference to the third possible implementation of the seventhaspect, in a fourth possible implementation, the transceiver module isfurther configured to after sending the cell addition requestacknowledgement message to the first base station, receive a celladdition complete message sent by the first base station, and theprocessing module is further configured to after the transceiver modulereceives the cell addition complete message, control the transceivermodule to communicate with the terminal by using the reconfiguredwireless connection.

With reference to any one of the seventh aspect, or the first to thefourth possible implementations of the seventh aspect, in a fifthpossible implementation, the processing module is further configured tobefore establishing the wireless connection between the terminal and thesecond cell, control the transceiver module to send a first indicationmessage to the terminal, so as to indicate that the second cell mayprovide communication for a same terminal together with the first cell,where the connection establishment process initiated by the terminal isinitiated by the terminal after the terminal receives the firstindication message and determines, according to the first indicationmessage, that the first cell may provide communication for the terminaltogether with the first cell.

With reference to any one of the seventh aspect, or the first to thefifth possible implementations of the seventh aspect, in a sixthpossible implementation, the first base station is a macro base stationor a small node, or the first base station includes a first node of thefirst cell and a first control node configured to control the firstnode, where the first node is configured to process transmission betweenthe terminal and the first control node, and the second base station isa small node, a macro base station, or a Wireless Fidelity WiFi accesspoint AP.

According to an eighth aspect, an embodiment of the present inventionprovides a cell access method, including when a terminal communicatingwith a first cell needs to communicate with a second cell, initiating,by the terminal, a connection establishment process, establishing, byusing the connection establishment process, a wireless connection bywhich the terminal communicates with the second cell, and accessing thesecond cell by using the established wireless connection, and afterreceiving a reconfiguration message sent by a first base station of thefirst cell, reconfiguring, by the terminal, the wireless connectionaccording to the reconfiguration message, and communicating with thesecond cell by using the reconfigured wireless connection, where thereconfiguration message is sent by the first base station to theterminal after the first base station determines, according to aterminal access indication message that is received from a second basestation of the second cell and is used to indicate that the terminalaccesses the second cell, that the terminal accesses the second cell,and after the first base station determines that the second base stationallows addition of the second cell as a cell communicating with theterminal.

With reference to the eighth aspect, in a first possible implementation,after the terminal reconfigures the wireless connection according to thereconfiguration message, and before the terminal communicates with thesecond cell by using the reconfigured wireless connection, the methodfurther includes sending, by the terminal, a reconfiguration completemessage to the first base station, so as to indicate to the first basestation that the terminal has completed reconfiguration of the wirelessconnection according to the reconfiguration message.

With reference to the eighth aspect or the first possible implementationof the eighth aspect, in a second possible implementation, before theterminal establishes the wireless connection to the second cell, themethod further includes measuring, by the terminal, a wireless signaltransmitted in the second cell, and determining, according to ameasurement result of the measuring, that the second cell is available.

With reference to the second possible implementation of the eighthaspect, in a third possible implementation, before the measuring, by theterminal, a wireless signal transmitted in the second cell, the methodfurther includes receiving, by the terminal, a measurement configurationmessage sent by the first base station, where the measurementconfiguration message includes cell identity information of the secondcell, and information about a decision condition used to determinewhether the second cell is available, and the measuring, by theterminal, a wireless signal sent in the second cell, and determining,according to a measurement result of the measuring, that the second cellis available includes measuring, by the terminal according to the cellidentity information of the second cell that is included in themeasurement configuration message, the wireless signal transmitted inthe second cell, and when the measurement result of the measuring meetsthe decision condition, determining that the second cell is available.

With reference to the second possible implementation of the eighthaspect, in a fourth possible implementation, before the measuring, bythe terminal, a wireless signal transmitted in the second cell, themethod further includes receiving, by the terminal, a measurementconfiguration message sent by the first base station, where themeasurement configuration message includes frequency information of thesecond cell, and information about a decision condition used todetermine whether the second cell is available, and the measuring, bythe terminal, a wireless signal transmitted in the second cell, anddetermining, according to a measurement result of the measuring, thatthe second cell is available includes measuring, by the terminalaccording to the frequency information of the second cell that isincluded in the measurement configuration message, the wireless signaltransmitted in the second cell, and when the measurement result of themeasuring meets the decision condition, determining that the second cellis available.

With reference to any one of the second to the fourth possibleimplementations of the eighth aspect, in a fifth possibleimplementation, before the measuring, by the terminal, a wireless signaltransmitted in the second cell, the method further includes receiving,by the terminal, a first indication message sent by the second basestation or the first base station, and determining, by the terminalaccording to the first indication message, that the second cell may beadded as a cell communicating with the terminal, where the firstindication message is used to indicate that the second cell may providecommunication for a same terminal together with the first cell.

With reference to any one of the eighth aspect, or the first to thefifth possible implementations of the eighth aspect, in a sixth possibleimplementation, the first base station is a macro base station or asmall node, or the first base station includes a first node of the firstcell and a first control node configured to control the first node,where the first node is configured to process transmission between theterminal and the first control node, and the second base station is asmall node, a macro base station, or a Wireless Fidelity WiFi accesspoint AP.

According to a ninth aspect, an embodiment of the present inventionprovides a cell access method, including receiving, by a first basestation of a first cell, a terminal access indication message that issent by a second base station of a second cell and is used to indicatethat a terminal communicating with the first cell accesses the secondcell, and after receiving the terminal access indication message, and ifdetermining that the second base station allows addition of the secondcell as a cell communicating with the terminal, sending, by the firstbase station, a reconfiguration message to the terminal, so as toinstruct the terminal to reconfigure, according to the reconfigurationmessage, a wireless connection established when the terminal accessesthe second cell, and communicate with the second cell by using theconfigured wireless connection.

With reference to the ninth aspect, in a first possible implementation,the terminal access indication message is further used to indicate thatthe second base station allows addition of the second cell as a cellcommunicating with the terminal, and the determining, by the first basestation, that the second base station allows addition of the second cellas a cell communicating with the terminal includes after receiving theterminal access indication message, determining, by the first basestation, that the second base station allows addition of the second cellas a cell communicating with the terminal.

With reference to the first possible implementation of the ninth aspect,in a second possible implementation, the terminal access indicationmessage carries a wireless connection parameter that is used toreconfigure the wireless connection, and the sending, by the first basestation, a reconfiguration message to the terminal includes adding, bythe first base station to the reconfiguration message, the wirelessconnection parameter obtained from the terminal access indicationmessage, and sending the reconfiguration message to the terminal, wherethe reconfiguration message is specifically used to instruct theterminal to reconfigure the wireless connection according to thewireless connection parameter, and communicate with the second cell byusing the configured wireless connection.

With reference to the ninth aspect, in a third possible implementation,after the first base station receives the terminal access indicationmessage, the method further includes sending, by the first base station,a cell addition request message to the second base station, so as torequest the second base station to add the second cell as a cellcommunicating with the terminal, and the determining, by the first basestation, that the second base station allows addition of the second cellas a cell communicating with the terminal includes after receiving acell addition request acknowledgement message sent by the second basestation in response to the cell addition request message, determining,by the first base station, that the second base station allows additionof the second cell as a cell communicating with the terminal.

With reference to the third possible implementation of the ninth aspect,in a fourth possible implementation, the cell addition requestacknowledgement message carries a wireless connection parameter that isused to reconfigure the wireless connection, and the sending, by thefirst base station, a reconfiguration message to the terminal includesadding, by the first base station to the reconfiguration message, thewireless connection parameter obtained from the cell addition requestacknowledgement message, and sending the reconfiguration message to theterminal, where the reconfiguration message is specifically used toinstruct the terminal to reconfigure the wireless connection accordingto the wireless connection parameter, and communicate with the secondcell by using the configured wireless connection.

With reference to any one of the ninth aspect, or the first to thefourth possible implementations of the ninth aspect, in a fifth possibleimplementation, after the first base station sends the reconfigurationmessage to the terminal, the method further includes receiving, by thefirst base station, a reconfiguration complete message sent by theterminal in response to the reconfiguration message, determining, by thefirst base station according to the reconfiguration complete message,that the terminal has completed reconfiguration of the wirelessconnection according to the reconfiguration message, and sending, by thefirst base station, a cell addition complete message to the second basestation, so as to indicate the second base station that the terminal hascompleted reconfiguration of the wireless connection.

With reference to any one of the ninth aspect, or the first to the fifthpossible implementations of the ninth aspect, in a sixth possibleimplementation, before the first base station receives the terminalaccess indication message, the method further includes sending, by thefirst base station, a measurement configuration message to the terminal,where the measurement configuration message includes cell identityinformation of the second cell, and information about a decisioncondition used to determine whether the second cell is available, so asto instruct the terminal to measure, according to the cell identityinformation of the second cell that is included in the measurementconfiguration message, a wireless signal transmitted in the second cell,and when a measurement result of the measuring meets the decisioncondition, determine that the second cell is available.

With reference to any one of the ninth aspect, or the first to the fifthpossible implementations of the ninth aspect, in a seventh possibleimplementation, before the first base station receives the terminalaccess indication message, the method further includes sending, by thefirst base station, a measurement configuration message to the terminal,where the measurement configuration message includes frequencyinformation of the second cell, and information about a decisioncondition used to determine whether the second cell is available, so asto instruct the terminal to measure, according to the frequencyinformation of the second cell that is included in the measurementconfiguration message, a wireless signal transmitted in the second cell,and when a measurement result of the measuring meets the decisioncondition, determine that the second cell is available.

With reference to the sixth or the seventh possible implementation ofthe ninth aspect, in an eighth possible implementation, before the firstbase station sends the measurement configuration message, the methodfurther includes sending, by the first base station, a first indicationmessage to the terminal, where the first indication message is used toindicate that the second cell may provide communication for a sameterminal together with the first cell.

With reference to any one of the ninth aspect, or the first to theeighth possible implementations of the ninth aspect, in a ninth possibleimplementation, the first base station is a macro base station or asmall node, or the first base station includes a first node of the firstcell and a first control node configured to control the first node,where the first node is configured to process transmission between theterminal and the first control node, and the second base station is asmall node, a macro base station, or a Wireless Fidelity WiFi accesspoint AP.

According to a tenth aspect, an embodiment of the present inventionprovides a cell access method, including establishing, by a second basestation of a second cell, a wireless connection between a terminal andthe second cell in a connection establishment process initiated by theterminal, and allowing the terminal to access the second cell by usingthe wireless connection, and after the terminal accesses the secondcell, sending, by the second base station, a terminal access indicationmessage to a first base station of a first cell communicating with theterminal, so as to indicate that the second cell needs to be added, forthe terminal, as a cell communicating with the terminal.

With reference to the tenth aspect, in a first possible implementation,the terminal access indication message is further used to indicate thatthe second base station allows addition of the second cell as a cellcommunicating with the terminal, and the sending, by the second basestation, the terminal access indication message to the first basestation includes adding, by the second base station to the terminalaccess indication message, a wireless connection parameter that is usedto reconfigure the wireless connection, so as to instruct the first basestation to instruct the terminal to reconfigure the wireless connectionaccording to the wireless connection parameter.

With reference to the first possible implementation of the tenth aspect,in a second possible implementation, after the second base station sendsthe terminal access indication message to the first base station, themethod further includes receiving, by the second base station, a celladdition complete message sent by the first base station, and afterreceiving the cell addition complete message, communicating, by thesecond base station, with the terminal by using the reconfiguredwireless connection.

With reference to the tenth aspect, in a third possible implementation,after the second base station sends the terminal access indicationmessage to the first base station, the method further includesreceiving, by the second base station, a cell addition request messagesent by the first base station, where the cell addition request messageis used to request the second base station to add the second cell as acell communicating with the terminal, and sending, by the second basestation, a cell addition request acknowledgement message to the firstbase station in response to the cell addition request message, so as toindicate that the second base station allows addition of the second cellas a cell communicating with the terminal, where the cell additionrequest acknowledgement message carries a wireless connection parameterthat is used to reconfigure the wireless connection, so as to instructthe first base station to instruct the terminal to reconfigure thewireless connection according to the wireless connection parameter.

With reference to the third possible implementation of the tenth aspect,in a fourth possible implementation, after the second base station sendsthe cell addition request acknowledgement message to the first basestation, the method further includes receiving, by the second basestation, a cell addition complete message sent by the first basestation, and after receiving the cell addition complete message,communicating, by the second base station, with the terminal by usingthe reconfigured wireless connection.

With reference to any one of the tenth aspect, or the first to thefourth possible implementations of the tenth aspect, in a fifth possibleimplementation, before the second base station establishes the wirelessconnection between the terminal and the second cell, the method furtherincludes sending, by the second base station, a first indication messageto the terminal, so as to indicate that the second cell may providecommunication for a same terminal together with the first cell, wherethe connection establishment process initiated by the terminal isinitiated by the terminal after the terminal receives the firstindication message and determines, according to the first indicationmessage, that the first cell may provide communication for the terminaltogether with the first cell.

With reference to any one of the tenth aspect, or the first to the fifthpossible implementations of the tenth aspect, in a sixth possibleimplementation, the first base station is a macro base station or asmall node, or the first base station includes a first node of the firstcell and a first control node configured to control the first node,where the first node is configured to process transmission between theterminal and the first control node, and the second base station is asmall node, a macro base station, or a Wireless Fidelity WiFi accesspoint AP.

According to an eleventh aspect, an embodiment of the present inventionprovides a terminal, including a processing module and a transceivermodule, where the processing module is configured to control thetransceiver module to report an address of the terminal to a locationserver, and the transceiver module is configured to receive an InternetProtocol IP packet sent by an application server in an Internetaccording to the address of the terminal, where the application serverobtains the address of the terminal from the location server, and thelocation server is configured to store the address of the terminal, andprovide the address of the terminal for the application server.

With reference to the eleventh aspect, in a first possibleimplementation, the processing module is specifically configured tocontrol the transceiver module to report the address of the terminal byusing control plane signaling.

With reference to the first possible implementation of the eleventhaspect, in a second possible implementation, if multiple datatransmission paths exist between the terminal and the applicationserver, the processing module is specifically configured to for each ofthe data transmission paths, control the transceiver module to report anaddress of the terminal on the path by using the control planesignaling.

With reference to the eleventh aspect, or the first or the secondpossible implementation of the eleventh aspect, in a third possibleimplementation, the address of the terminal includes at least one of thefollowing addresses a public Internet Protocol IP address of theterminal, an IP address of an access gateway to which the terminal isconnected, or an identity of an access gateway to which the terminal isconnected, where the terminal accesses the Internet by using the accessgateway to which the terminal is connected, and performs packettransmission with the application server in the Internet.

With reference to the eleventh aspect, in a fourth possibleimplementation, the processing module is specifically configured tocontrol the transceiver module to send an Internet Protocol IP packet tothe location server, use a source IP address in the sent IP packet asthe address of the terminal, and report the address of the terminal tothe location server.

With reference to the fourth possible implementation of the eleventhaspect, in a fifth possible implementation, if multiple datatransmission paths exist between the terminal and the applicationserver, the processing module is specifically configured to for each ofthe multiple data transmission paths, control the transceiver module tosend an Internet Protocol IP packet to the location server by using thedata transmission path, use a source IP address in the sent IP packet asan address of the terminal on the data transmission path, and report theaddress of the terminal to the location server.

With reference to any one of the eleventh aspect, or the first to thefifth possible implementations of the eleventh aspect, in a sixthpossible implementation, the location server is a server that is in theInternet and that is independent of the application server, or thelocation server is located in the application server.

With reference to any one of the eleventh aspect, or the first to thesixth possible implementations of the eleventh aspect, in a seventhpossible implementation, the processing module is specificallyconfigured to control the transceiver module to periodically report theaddress of the terminal to the location server, and/or control thetransceiver module to report the address of the terminal to the locationserver when a path from the terminal to the application server or thelocation server changes.

With reference to any one of the eleventh aspect, or the first to theseventh possible implementations of the eleventh aspect, in an eighthpossible implementation, the processing module is further configured tobefore controlling the transceiver module to report the address of theterminal to the location server, select a to-be-accessed networkaccording to at least one of the following factors a service type of aservice to be established by the terminal, a quality of service QoSrequirement of a service to be established by the terminal, or a presetnetwork to be preferably accessed by the terminal, and the processingmodule is specifically configured to control the transceiver module toreport, to the location server, an address of the terminal in eachto-be-accessed network selected by the terminal.

According to a twelfth aspect, an embodiment of the present inventionprovides a location server, including a transceiver module, configuredto receive an address of a terminal that is reported by the terminal,and a processing module, configured to notify, an application serverperforming data transmission with the terminal, of the address of theterminal that is received by the transceiver module, so that theapplication server sends an Internet Protocol IP packet to the terminalaccording to the address of the terminal.

With reference to the twelfth aspect, in a first possibleimplementation, the processing module is specifically configured toafter receiving, by using the transceiver module, a request message thatis sent by the application server and is for requesting the address ofthe terminal, notify, the application server performing datatransmission with the terminal, of the address of the terminal that isreceived by the transceiver module.

With reference to the twelfth aspect or the first possibleimplementation of the twelfth aspect, in a second possibleimplementation, the transceiver module is specifically configured toreceive the address of the terminal that is reported by the terminal byusing control plane signaling.

With reference to the second possible implementation of the twelfthaspect, in a third possible implementation, the transceiver module isspecifically configured to receive an address that is of the terminal oneach of multiple data transmission paths existing between the terminaland the application server and that is reported by the terminal for thepath by using the control plane signaling.

With reference to any one of the twelfth aspect, or the first to thethird possible implementations of the twelfth aspect, in a fourthpossible implementation, the address of the terminal includes at leastone of the following addresses: a public Internet Protocol IP address ofthe terminal, an IP address of an access gateway to which the terminalis connected, or an identity of an access gateway to which the terminalis connected, where the terminal accesses an Internet by using theaccess gateway to which the terminal is connected, and performs packettransmission with the application server in the Internet.

With reference to the twelfth aspect or the first possibleimplementation of the twelfth aspect, in a fifth possibleimplementation, the transceiver module is specifically configured toreceive an IP packet sent by the terminal, and use a source IP addressin the received IP packet as the address of the terminal.

With reference to the fifth possible implementation of the twelfthaspect, in a sixth possible implementation, the transceiver module isspecifically configured to receive an IP packet sent by the terminal byusing each of multiple data transmission paths existing between theterminal and the application server, and use a source IP address in thereceived IP packet as an address of the terminal on the datatransmission path.

With reference to any one of the twelfth aspect, or the first to thesixth possible implementations of the twelfth aspect, in a seventhpossible implementation, the location server is a server that is in theInternet and that is independent of the application server, or thelocation server is located in the application server.

With reference to any one of the twelfth aspect, or the first to theseventh possible implementations of the twelfth aspect, in an eighthpossible implementation, the transceiver module is specificallyconfigured to receive the address of the terminal that is periodicallyreported by the terminal, and/or receive the address of the terminalthat is reported by the terminal when a path from the terminal to theapplication server or the location server changes.

According to a thirteenth aspect, an embodiment of the present inventionprovides a data transmission method, including reporting, by a terminal,an address of the terminal to a location server, and receiving, by theterminal, an Internet Protocol IP packet sent by an application serverin an Internet according to the address of the terminal, where theapplication server obtains the address of the terminal from the locationserver, and the location server is configured to store the address ofthe terminal, and provide the address of the terminal for theapplication server.

With reference to the thirteenth aspect, in a first possibleimplementation, the reporting, by a terminal, an address of the terminalto a location server includes reporting, by the terminal, the address ofthe terminal by using control plane signaling.

With reference to the first possible implementation of the thirteenthaspect, in a second possible implementation, if multiple datatransmission paths exist between the terminal and the applicationserver, the reporting, by the terminal, the address of the terminal byusing control plane signaling includes for each of the data transmissionpaths, reporting, by the terminal, an address of the terminal on thepath by using the control plane signaling.

With reference to the thirteenth aspect, or the first or the secondpossible implementation of the thirteenth aspect, in a third possibleimplementation, the address of the terminal includes at least one of thefollowing addresses: a public Internet Protocol IP address of theterminal, an IP address of an access gateway to which the terminal isconnected, or an identity of an access gateway to which the terminal isconnected, where the terminal accesses the Internet by using the accessgateway to which the terminal is connected, and performs packettransmission with the application server in the Internet.

With reference to the thirteenth aspect, in a fourth possibleimplementation, the reporting, by a terminal, an address of the terminalto a location server includes sending, by the terminal, an InternetProtocol IP packet to the location server, using a source IP address inthe sent IP packet as the address of the terminal, and reporting theaddress of the terminal to the location server.

With reference to the fourth possible implementation of the thirteenthaspect, in a fifth possible implementation, if multiple datatransmission paths exist between the terminal and the applicationserver, the reporting, by a terminal, an address of the terminal to alocation server includes for each of the multiple data transmissionpaths, sending, by the terminal, an Internet Protocol IP packet to thelocation server by using the data transmission path, using a source IPaddress in the sent IP packet as an address of the terminal on the datatransmission path, and reporting the address of the terminal to thelocation server.

With reference to any one of the thirteenth aspect, or the first to thefifth possible implementations of the thirteenth aspect, in a sixthpossible implementation, the location server is a server that is in theInternet and that is independent of the application server, or thelocation server is located in the application server.

With reference to any one of the thirteenth aspect, or the first to thesixth possible implementations of the thirteenth aspect, in a seventhpossible implementation, the reporting, by a terminal, an address of theterminal to a location server includes periodically reporting, by theterminal, the address of the terminal to the location server, and/orreporting, by the terminal, the address of the terminal to the locationserver when a path from the terminal to the application server or thelocation server changes.

With reference to any one of the thirteenth aspect, or the first to theseventh possible implementations of the thirteenth aspect, in an eighthpossible implementation, before the reporting, by a terminal, an addressof the terminal to a location server, the method further includes:selecting, by the terminal, a to-be-accessed network according to atleast one of the following factors: a service type of a service to beestablished by the terminal, a quality of service QoS requirement of aservice to be established by the terminal, or a preset network to bepreferably accessed by the terminal, and the reporting, by a terminal,an address of the terminal to a location server includes reporting, bythe terminal to the location server, an address of the terminal in eachto-be-accessed network selected by the terminal.

According to a fourteenth aspect, an embodiment of the present inventionprovides a data transmission method, including receiving, by a locationserver, an address of a terminal that is reported by the terminal, andnotifying, by the location server, an application server performing datatransmission with the terminal, of the received address of the terminal,so that the application server sends an Internet Protocol IP packet tothe terminal according to the address of the terminal.

With reference to the fourteenth aspect, in a first possibleimplementation, the notifying, by the location server, an applicationserver performing data transmission with the terminal, of the receivedaddress of the terminal includes after receiving a request message thatis sent by the application server and is for requesting the address ofthe terminal, notifying, by the location server, the application serverperforming data transmission with the terminal, of the received addressof the terminal.

With reference to the fourteenth aspect or the first possibleimplementation of the fourteenth aspect, in a second possibleimplementation, the receiving, by a location server, an address of aterminal that is reported by the terminal includes receiving, by thelocation server, the address of the terminal that is reported by theterminal by using control plane signaling.

With reference to the second possible implementation of the fourteenthaspect, in a third possible implementation, the receiving, by thelocation server, the address of the terminal that is reported by theterminal by using control plane signaling includes receiving, by thelocation server, an address that is of the terminal on each of multipledata transmission paths existing between the terminal and theapplication server and that is reported by the terminal for the path byusing the control plane signaling.

With reference to any one of the fourteenth aspect, or the first to thethird possible implementations of the fourteenth aspect, in a fourthpossible implementation, the address of the terminal includes at leastone of the following addresses: a public Internet Protocol IP address ofthe terminal, an IP address of an access gateway to which the terminalis connected, or an identity of an access gateway to which the terminalis connected, where the terminal accesses an Internet by using theaccess gateway to which the terminal is connected, and performs packettransmission with the application server in the Internet.

With reference to the fourteenth aspect or the first possibleimplementation of the fourteenth aspect, in a fifth possibleimplementation, the receiving, by a location server, an address of aterminal that is reported by the terminal includes receiving, by thelocation server, an IP packet sent by the terminal, and using a sourceIP address in the received IP packet as the address of the terminal.

With reference to the fifth possible implementation of the fourteenthaspect, in a sixth possible implementation, the receiving, by thelocation server, an IP packet sent by the terminal, and using a sourceIP address in the received IP packet as the address of the terminalincludes receiving, by the location server, an IP packet sent by theterminal by using each of multiple data transmission paths existingbetween the terminal and the application server, and using a source IPaddress in the received IP packet as an address of the terminal on thedata transmission path.

With reference to any one of the fourteenth aspect, or the first to thesixth possible implementations of the fourteenth aspect, in a seventhpossible implementation, the location server is a server that is in theInternet and that is independent of the application server, or thelocation server is located in the application server.

With reference to any one of the fourteenth aspect, or the first to theseventh possible implementations of the fourteenth aspect, in an eighthpossible implementation, the receiving, by a location server, an addressof a terminal that is reported by the terminal includes receiving, bythe location server, the address of the terminal that is periodicallyreported by the terminal, and/or receiving, by the location server, theaddress of the terminal that is reported by the terminal when a pathfrom the terminal to the application server or the location serverchanges.

In any one of solutions provided in the first to the fourth aspects, aterminal autonomously selects a to-be-accessed second cell, and activelyrequests a first base station to add a second cell. Compared with asolution that is in a current cell handover procedure and in which aterminal sends a measurement report and a base station performs handoverdecision, partial processing is performed by the terminal, so thatprocessing of a network device such as a base station can be reduced,and implementation complexity of the network device can be reduced.

In any one of solutions provided in the fifth to the tenth aspects, aterminal first accesses a second cell, and a second base station of thesecond cell notifies a first base station of the access of the terminal.In this optional solution, the terminal can also autonomously select ato-be-accessed second cell.

In any one of solutions provided in the eleventh to the fourteenthaspects, a terminal reports an address of the terminal to a locationserver. The location server sends the received address of the terminalto an application server performing data transmission with the terminal,or an application server obtains the address of the terminal from thelocation server. The application server sends an IP packet to theterminal according to the obtained address of the terminal. Theapplication server obtains the address of the terminal from the locationserver, so that the application server can send an IP packet to theterminal according to the obtained address of the terminal.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a schematic diagram of a cell handover procedure;

FIG. 2 is a schematic structural diagram of a wireless communicationssystem according to an embodiment of the present invention;

FIG. 3 is a flowchart of an optional implementation of a first cellaccess solution according to an embodiment of the present invention;

FIG. 4 is a flowchart of a second cell access solution in a firstoptional implementation according to an embodiment of the presentinvention;

FIG. 5 is a flowchart of a second cell access solution in a secondoptional implementation according to an embodiment of the presentinvention;

FIG. 6 is a diagram of a network architecture that is of a network andto which a data transmission solution may be applied according to anembodiment of the present invention;

FIG. 7 is a flowchart of an optional implementation of a datatransmission solution according to an embodiment of the presentinvention;

FIG. 8 is a schematic structural diagram of a first terminal accordingto an embodiment of the present invention;

FIG. 9 is a schematic structural diagram of a second terminal accordingto an embodiment of the present invention;

FIG. 10 is a schematic structural diagram of a first type of first basestation according to an embodiment of the present invention;

FIG. 11 is a schematic structural diagram of a second type of first basestation according to an embodiment of the present invention;

FIG. 12 is a flowchart of a first cell access method according to anembodiment of the present invention;

FIG. 13 is a flowchart of a second cell access method according to anembodiment of the present invention;

FIG. 14 is a schematic structural diagram of a third terminal accordingto an embodiment of the present invention;

FIG. 15 is a schematic structural diagram of a fourth terminal accordingto an embodiment of the present invention;

FIG. 16 is a schematic structural diagram of a third type of first basestation according to an embodiment of the present invention;

FIG. 17 is a schematic structural diagram of a fourth type of first basestation according to an embodiment of the present invention;

FIG. 18 is a schematic structural diagram of a first type of second basestation according to an embodiment of the present invention;

FIG. 19 is a schematic structural diagram of a second type of secondbase station according to an embodiment of the present invention;

FIG. 20 is a flowchart of a third cell access method according to anembodiment of the present invention;

FIG. 21 is a flowchart of a fourth cell access method according to anembodiment of the present invention;

FIG. 22 is a flowchart of a fifth cell access method according to anembodiment of the present invention;

FIG. 23 is a schematic structural diagram of a fifth terminal accordingto an embodiment of the present invention;

FIG. 24 is a schematic structural diagram of a sixth terminal accordingto an embodiment of the present invention;

FIG. 25 is a schematic structural diagram of a first location serveraccording to an embodiment of the present invention;

FIG. 26 is a schematic structural diagram of a second location serveraccording to an embodiment of the present invention;

FIG. 27 is a flowchart of a first data transmission method according toan embodiment of the present invention; and

FIG. 28 is a flowchart of a second data transmission method according toan embodiment of the present invention.

DETAILED DESCRIPTION OF ILLUSTRATIVE EMBODIMENTS

Embodiments of the present invention provide a terminal, a base station,and a cell access method, so as to enable the terminal to autonomouslyaccess a cell, and resolve the foregoing problem: Because a networkdevice strictly controls the terminal, network implementation iscomplex, and deployment and maintenance are not easy to perform.

One optional solution includes the following content:

When a terminal communicating with a first cell needs to communicatewith a second cell, the terminal sends a first cell addition requestmessage to a first base station of the first cell, after receiving thefirst cell addition request message, the first base station sends asecond cell addition request message to a second base station of thesecond cell, so as to request to add the second cell as a cellcommunicating with the terminal, and after receiving a cell additionrequest acknowledgement message sent by the second base station inresponse to the second cell addition request message, the first basestation sends, to the terminal, a configuration message that is used toconfigure a wireless connection by which the terminal communicates withthe second cell, so as to instruct the terminal to configure, accordingto the configuration message, the wireless connection by which theterminal communicates with the second cell, and access the second cell.

As is described above, in a current cell handover procedure, a terminalsends a measurement report, and a base station performs handoverdecision. However, in this optional solution, the terminal autonomouslyselects a to-be-accessed second cell, and actively requests the firstbase station to add a second cell. Partial processing is performed bythe terminal, so that processing of a network device such as a basestation can be reduced, and implementation complexity of the networkdevice can be reduced.

Another optional solution includes the following content:

When a terminal communicating with a first cell needs to communicatewith a second cell, the terminal accesses the second cell, after theterminal accesses the second cell, a second base station of the secondcell sends a terminal access indication message to a first base stationof the first cell, so as to indicate that the terminal accesses thesecond cell, and after receiving the terminal access indication message,and if determining that the second base station allows addition of thesecond cell as a cell communicating with the terminal, the first basestation sends a reconfiguration message to the terminal, so as toinstruct the terminal to reconfigure, according to the reconfigurationmessage, a wireless connection established when the terminal accessesthe second cell, and communicate with the second cell by using theconfigured wireless connection.

Similarly, in this optional solution, the terminal can also autonomouslyselect a to-be-accessed second cell. A difference between this optionalsolution and the former optional solution is: In the former optionalsolution, the terminal sends a message to the first base station, so asto request to access the second cell, in this solution, the terminalfirst accesses the second cell, and the second base station of thesecond cell notifies the first base station of the access of theterminal.

In either of the two optional solutions, the terminal can autonomouslyaccess the second cell.

Further, the embodiments of the present invention provide a terminal, alocation server, and a data transmission method, so as to enable anapplication server to send an IP packet to the terminal.

A terminal reports an address of the terminal to a location server. Thelocation server sends the received address of the terminal to anapplication server performing data transmission with the terminal, or anapplication server obtains the address of the terminal from the locationserver. The application server sends an IP packet to the terminalaccording to the obtained address of the terminal.

The application server obtains the address of the terminal from thelocation server, so that the application server can send an IP packet tothe terminal according to the obtained address of the terminal.

Basic concepts used in the embodiments of the present invention aredescribed in the following.

These basic concepts include a wireless communications system, awireless communications standard, a base station, a terminal, a firstserver, a second server, an access node, a control plane anchor, a userplane anchor, radio resource control (Radio Resource Control, RRC)signaling, and quality of service (Quality of Service, QoS) management.These concepts are described one by one in the following.

1. Wireless Communications System

Generally, the wireless communications system is a system in whichtransmission is performed in some or all communications linkswirelessly. A common type of wireless communications system generallyincludes:

at least one terminal, a radio access network, and a core network.

The core network is connected to an external application server oranother communications system, implements communication between theterminal and the application server and/or the another communicationssystem, and manages user information, quality of service, and the likeof the terminal.

The radio access network is wirelessly connected to the terminal byusing an air interface (air interface) such as a Uu interface, so thatthe terminal can access the network.

A wireless connection may also be referred to as an air interfaceconnection. The terminal keeps a wireless connection to a base stationor an access node in the radio access network, and may communicate withthe base station by using the wireless connection.

2. Wireless Communications Standard.

Different wireless communications standards may be used in differentwireless communications systems. A wireless communications standardapplicable to the embodiments of the present invention includes but isnot limited to the following standards: a Global System for MobileCommunications (GSM for short), Code Division Multiple Access (CDMA forshort) IS-95, Code Division Multiple Access (CDMA for short) 2000, TimeDivision-Synchronous Code Division Multiple Access (TD-SCDMA for short),Wideband Code Division Multiple Access (WCDMA for short), Time DivisionDuplex-Long Term Evolution (TDD LTE for short), Frequency DivisionDuplex-Long Term Evolution (FDD LTE for short), Long Term EvolutionAdvanced (LTE-advanced for short), a personal handy-phone system(Personal Handy-phone System, PHS), Wireless Fidelity (WirelessFidelity, WiFi) specified by the 802.11 family of protocols, WorldwideInteroperability for Microwave Access (Worldwide Interoperability forMicrowave Access, WiMAX), and a short-range wireless communicationssystem such as Bluetooth.

The embodiments of the present invention intend to provide a flattenednetwork architecture. Persons skilled in the art may learn that thenetwork architecture is applicable to not only various current possiblewireless communications standards, but also various communicationsstandards in a future wireless communications system.

3. Base Station

The base station is located in a radio access network in a wirelesscommunications system. The base station communicates with a terminal byusing an air interface, so that the terminal can access the network.

4. Terminal

The terminal may be user equipment, and includes but is not limited to amobile phone, a tablet computer, a personal digital assistant (PersonalDigital Assistant, PDA), a point of sale (Point of Sales, POS), and anin-vehicle computer.

For example, for an LTE system such as a TDD LTE system, an FDD LTEsystem, or an LTE-A system, the base station may be an evolved NodeB(eNodeB), and the terminal may be UE. For a TD-SCDMA system or a WCDMAsystem, the base station may include a NodeB (NodeB) or include a NodeBand a radio network controller (RNC), and the terminal may be UE. For aGSM system, the base station may include a base transceiver station(BTS) or include a BTS and a base station controller (BSC), and theterminal is a mobile station (MS). For a WiFi system, the base stationmay include an access point (AP) and/or an access controller (AC), andthe terminal may be a station (STA for short).

5. First Server

The first server is configured to provide an application service for aterminal covered by the radio access network. For example, anapplication server provides a service for a user corresponding to theterminal, and the terminal receives service data from the applicationserver or sends service data to the application server.

6. Second Server

The second server is configured to perform user information managementon the terminal covered by the radio access network, for example,maintain subscription information and implement a function of an HSS ina current EPC.

Optionally, the second server may further perform user authentication,location update, and the like according to user information, to meet arequirement of a control plane anchor. The second server may beconsidered as a part in the core network. For example, the second servermay be the following mobile network operator server 204 shown in FIG. 2.

User information managed by the second server may include thesubscription information, user location information, and the like, andthe second server stores the user information. Optionally, the secondserver may further perform user authentication, location update, and thelike according to the user information, to meet the requirement of thecontrol plane anchor.

The first server and the second server are collectively referred to asbusiness support systems (Business Support System).

7. Access Node

The access node keeps a wireless connection to the at least one terminalin the radio access network, and implements communication between theterminal and the first server by using the wireless connection betweenthe access node and the terminal.

The access node may be a base station in a cellular wirelesscommunications system (different from a WiFi system), and may include amacro base station, a small node, or even a light node that implementsonly some air interface functions, or may be another node such as a WiFiAP in the WiFi system.

The small node may be a base station that has a relatively smallcommunication coverage area and a relatively low maximum transmit power,for example, a small cell, a pico cell, a home eNodeB, a home NodeB, ora femto cell. Compared with the macro base station, the small node haslow-power, small-volume, and easy-to-deploy advantages, and may beflexibly deployed at a lamp pole, on a billboard, or indoors. The smallnode may be configured to fill coverage holes of wireless coverage, andmay also be configured to expand a capacity of the radio access network.A communication coverage radius of the small node is usually less than apreset threshold such as 100 m, and a maximum transmit power of themicro base station is usually less than a preset power threshold such as10 w.

The light node may be a base station that does not implement a completeair interface protocol stack. For example, in an LTE system, a basestation that implements only a PHY layer, a MAC layer, and an RLC layerin an LTE air interface protocol stack but does not implement a PDCPlayer and an RRC layer may be referred to as the light node.

8. Control Plane Anchor

The control plane anchor may control the terminal covered by the radioaccess network to establish a wireless connection to one or more accessnodes, and enable, by exchanging information with the second server, thesecond server to perform user information management on the terminal.

The control plane anchor may be a base station in the cellular wirelesscommunications system, for example, a macro base station, or may beanother control-plane centralized control point, for example, acontroller in an access network implemented based on software-definednetworking (SDN for short).

9. User Plane Anchor

The user plane anchor may send, to the first server, user plane datathat is forwarded by one or more access nodes and that is from aterminal keeping a wireless connection to the one or more access nodes,and may send, to the terminal by using the access node connected to theterminal, user plane data that is received from the first server andthat is to be sent to the terminal keeping a wireless connection to theone or more access nodes.

The user plane anchor may be a user-plane convergence node such as auniversal gateway (UGW for short). For example, the UGW may be a localgateway (LGW for short). The LGW may be located in the base station, orthe LGW and the base station may be deployed together.

The user plane anchor and the control plane anchor may be collectivelyreferred to as access anchors. An access anchor may be both a user planeanchor and a control plane anchor, or may be only a user plane anchor,or may be only a control plane anchor.

10. Network Architecture of a Radio Access Network Including an AccessNode and a Control Plane Anchor and/or a User Plane Anchor

When this network architecture is used, a terminal keeps a wirelessconnection to the access node, for example, an RRC connection. If thecontrol plane anchor exists, the access node is connected to the controlplane anchor. If the user plane anchor exists, the access node isconnected to the user plane anchor.

11. RRC Signaling

In a current LTE system, an RRC layer is the topmost control-plane layerin a radio access network protocol stack, and is a control planeprotocol. The RRC layer may provide services such as connectionmanagement and message transfer for a non-access stratum, provide aparameter configuration function for each lower-layer protocol entity inthe radio access network, and take responsibility for measurement,control, and the like related to mobility management of UE.

The embodiments of the present invention are described in detail in thefollowing with reference to the accompanying drawings. First, a firstcell access solution and a second cell access solution that are providedin the embodiments of the present invention are described. Next, a datatransmission solution provided in the embodiments of the presentinvention is described.

First Cell Access Solution

The first cell access solution may be applied to a wirelesscommunications system shown in FIG. 2. The wireless communicationssystem includes a terminal 201, a first base station 202, and a secondbase station 203. The terminal 201 communicates with a first cell of thefirst base station 202.

The terminal 201 is configured to when the terminal 201 needs tocommunicate with a second cell of the second base station 203, send afirst cell addition request message to the first base station 202, forexample, a secondary-cell addition request message sent by the terminal201 in step S304 in FIG. 3.

The first base station 202 is configured to after receiving the firstcell addition request message, send a second cell addition requestmessage to the second base station 203, for example, a secondary-celladdition request message sent by the first base station 202 in step S305in FIG. 3, so as to request to add the second cell as a cellcommunicating with the terminal.

The second base station 203 is configured to after receiving the secondcell addition request message, if it is determined that the second cellmay be added as a cell communicating with the terminal 201, send a celladdition request acknowledgement message to the first base station 202in response to the second cell addition request message.

The first base station 202 is further configured to after receiving thecell addition request acknowledgement message sent by the second basestation 203, send, to the terminal 201, a configuration message that isused to configure a wireless connection by which the terminal 201communicates with the second cell, for example, an RRC reconfigurationmessage sent by the first base station 202 in step S307 in FIG. 3.

The terminal 201 is further configured to configure, according to theconfiguration message sent by the first base station 202, the wirelessconnection by which the terminal 201 communicates with the second cell,and access the second cell.

Optionally, the wireless communications system may further include amobile network operator server 204, configured to perform authenticationon the terminal 201.

With reference to a procedure shown in FIG. 3, a first cell accesssolution provided in an embodiment of the present invention is describedin detail in the following.

The procedure shown in FIG. 3 includes the following steps.

S301. A terminal 201 accesses a first cell of a first base station 202.

After the terminal 201 is powered on, the terminal 201 may access thefirst base station 202 by using an RRC connection establishment process.In an access process, the terminal 201 may report an autonomous accesscapability of the terminal 201 or a user preference. The first basestation 202 and/or a mobile network operator server 204 does not performmobility management and/or service continuity management for a useraccording to the capability or the user preference.

After the access, the terminal initiates a user authentication processbetween the terminal and the mobile network operator server 204. Themobile network operator server 204 may send subscription information tothe first base station 202. The first base station 202 may perform datatransmission QoS management according to the subscription information,so as to preferably ensure a high-priority user and/or a high-priorityservice.

S302. The terminal 201 reads system information of a second cell of asecond base station 203.

The system information includes information about a base station or acell that may perform carrier aggregation (Carrier Aggregation, CA) ordual connectivity (Dual Connectivity, DC) with the second cell, forexample, a base station identity that is of the first base station 202and is used to indicate that the second cell may perform dualconnectivity with any cell of the first base station 202.

The terminal 201 determines, according to the obtained systeminformation, that the second cell may be added as a cell communicatingwith the terminal 201. Therefore, the system information may also beconsidered as an indication message indicating the terminal 201 that thesecond cell may provide communication for a same terminal together withthe first cell.

Alternatively, an indication message may be sent by the first basestation 202, and the indication message includes information about abase station or a cell that may perform carrier aggregation or dualconnectivity with the first base station 202 or the first cell. In thiscase, the terminal 201 may also determine, according to the indicationmessage sent by the first base station 202, that the second cell may beadded as a cell communicating with the terminal 201.

Before step S302, a resource negotiation and interference coordinationprocess may exist between the first base station 202 and the second basestation 203. By coordinating radio resources used between base stations,inter-station interference is reduced, and radio resource utilization isimproved.

S303. The terminal 201 detects that the second cell of the second basestation 203 can be used.

The terminal 201 discovers the second cell by means of network searchand/or measurement, and determines whether the second cell is available.Before this step, the first base station 202 may send a measurementconfiguration message to the terminal 201, so as to indicate, to theterminal 201, a to-be-measured cell, a decision threshold that is foreach to-be-measured cell and is for determining whether the cell isavailable, and the like. The terminal 201 may determine, according to apre-defined decision criterion used to determine whether a cell isavailable, whether a cell is available, for example, a wireless networktype and/or a pre-defined cell signal strength threshold.

For example, the measurement configuration message may include cellidentity information of the second cell, and information about adecision condition used to determine whether the second cell isavailable. The terminal 201 measures, according to the cell identityinformation of the second cell that is included in the measurementconfiguration message, a wireless signal transmitted in the second cell,and when a measurement result meets the decision condition, determinesthat the second cell is available.

For another example, the measurement configuration message may includefrequency information of the second cell, and information about adecision condition used to determine whether the second cell isavailable. The terminal measures, according to the frequency informationof the second cell that is included in the measurement configurationmessage, a wireless signal transmitted in the second cell, and when ameasurement result meets the decision condition, determines that thesecond cell is available.

S304. The terminal 201 sends a secondary-cell addition request messageto the first base station 202.

After the terminal 201 detects that the second cell is available, anddetermines, according to the information obtained in step S302, that thesecond cell may provide communication for the terminal 201 together withthe first cell, for example, the second cell may perform dualconnectivity with the first cell, the terminal 201 initiates a processof adding a secondary cell for dual connectivity. The secondary-celladdition request message includes indication information of ato-be-added secondary cell, that is, the second cell, for example, aphysical cell identifier (Physical Cell Identifier, PCI) of the secondcell.

Herein, it should be noted that both the process of adding a secondarycell and the secondary-cell addition request message are examples, andany message that can implement addition of the second cell as a cellcommunicating with the terminal 201 may be applied to the first cellaccess solution provided in this embodiment of the present invention. Inaddition, names of other messages in this solution are also examplesonly, and any message that can implement a corresponding function may beconsidered as an optional implementation in this solution.

S305. The first base station 202 sends a “secondary-cell additionrequest” message to the second base station 203.

The message is used to request to add the second cell as a cellcommunicating with the terminal 201. Optionally, the message may includeinformation about the to-be-added second cell, for example, the identityinformation or the frequency information of the second cell. Inaddition, the message may include parameter information for performing,between the first base station 202 and the second base station 203,uplink power control and negotiation of a maximum bit rate and the likefor the terminal 201, and bearer configuration information.

S306. The second base station 203 sends a “secondary-cell additionrequest acknowledgement” message to the first base station 202.

The second base station 203 indicates, by using the message, the firstbase station 202 that the second cell may be added as a cellcommunicating with the terminal 201. The message may further includeconfiguration information for the terminal 201 on the second basestation 203.

S307. The first base station 202 sends an “RRC reconfiguration” messageto the terminal 201.

The message is used to notify the terminal 201 that the second cell isto be added as a cell communicating with the terminal 201, for example,as a secondary cell for dual connectivity. The message may carry theconfiguration information obtained in step S306. The terminal 201 mayconfigure, according to the information, a wireless connection by whichthe terminal 201 communicates with the second cell.

S308. The terminal 201 sends an RRC reconfiguration complete message tothe first base station 202.

The message is used to indicate that the terminal 201 has completedconfiguration of the wireless connection according to the configurationinformation in step S307, for example, indicate that the terminal 201has configured the second cell as a secondary cell for dualconnectivity.

S309. The first base station 202 sends an RRC reconfiguration completemessage to the second base station 203.

After receiving the RRC reconfiguration complete message sent by theterminal, the first base station 202 sends an RRC reconfigurationcomplete message to the second base station 203, so as to indicate thesecond base station 203 that the terminal 201 has configured the secondcell as a secondary cell for dual connectivity.

S310. The terminal initiates a random access process to the second cell,and accesses the second cell.

There is no strict sequence between step S310 and step S308.

After accessing the second cell, the terminal 201 can perform datatransmission by using both the first cell and the second cell, andimplement dual connectivity.

Second Cell Access Solution

A difference between the second cell solution and the first cell accesssolution is: In the first cell access solution, a terminal 201 sends amessage to a first base station 202, so as to request to access a secondcell, in the second cell access solution, the terminal 201 firstaccesses the second cell, and a second base station 203 of the secondcell notifies the first base station 202 of the access of the terminal.

The second cell access solution may also be applied to the wirelesscommunications system shown in FIG. 2.

A terminal 201 is configured to when the terminal 201 needs tocommunicate with a second cell of a second base station 203, initiate aconnection establishment process, establish, by using the connectionestablishment process, a wireless connection by which the terminal 201communicates with the second cell, and access the second cell by usingthe established wireless connection.

The second base station 203 is configured to after the terminal 201accesses the second cell, send a terminal access indication message to afirst base station 202 of a first cell, for example, a terminal accessindication message in step S405 in FIG. 4, so as to indicate that thesecond cell needs to be added, for the terminal 201, as a cellcommunicating with the terminal 201.

The first base station 202 is configured to after receiving the terminalaccess indication message sent by the second base station 203, and ifdetermining that the second base station 203 allows addition of thesecond cell as a cell communicating with the terminal 201, send areconfiguration message to the terminal 201, for example, an RRCreconfiguration message in step S408 in FIG. 4.

The terminal 201 is further configured to reconfigure, according to thereconfiguration message, the wireless connection established when theterminal 201 accesses the second cell, and communicate with the secondcell by using the configured wireless connection.

Optionally, the wireless communications system may further include amobile network operator server 204, configured to perform authenticationon the terminal 201.

With reference to a procedure shown in FIG. 4, a second cell accesssolution provided in an embodiment of the present invention is describedin detail in the following.

An example that a configuration message sent by a first base station 202to a terminal 201 is an RRC reconfiguration message is used in theprocedure shown in FIG. 4.

The procedure shown in FIG. 4 includes the following steps.

S401. A terminal 201 accesses a first cell of a first base station 202.

This step is the same as step S301.

S402. The terminal 201 reads system information of a second cell of asecond base station 203.

This step is the same as that in step S302.

S403. The terminal 201 detects that the second cell of the second basestation 203 can be used.

This step is the same as that in step S303.

S404. The terminal 201 initiates an RRC connection establishment processto the second cell of the second base station 203.

The terminal 201 establishes, by using the initiated RRC connectionestablishment process, a wireless connection by which the terminal 201communicates with the second cell, and accesses the second cell by usingthe established wireless connection.

S405. The second base station 203 sends a terminal access indicationmessage to the first base station 202.

In a process in which the terminal 201 accesses the second cell or afterthe terminal 201 accesses second cell, the second base station 203 maysend, to the first base station 202, the terminal access indicationmessage that includes a terminal identity of the terminal 201.

The terminal identity of the terminal 201 may include at one of thefollowing identifiers:

a Medium Access Control (Medium Access Control, MAC) address of theterminal 201, an IP address allocated by the first base station 202 tothe terminal 201, a cell radio network temporary identifier (C-RNTI forshort) allocated by the first base station 202 to the terminal 201, atemporary mobile subscriber identity (Temporary Mobile SubscriberIdentity, TMSI) allocated by the first base station 202 to the terminal201, or an international mobile subscriber identity (InternationalMobile Subscriber Identity, IMSI).

The second base station 203 may obtain, from the first base station 202,indication information used to indicate whether the terminal accessindication message needs to be sent to the first base station 202 whenthe terminal 201 accesses the second cell.

S406. The first base station 202 sends a “secondary-cell additionrequest” message to the second base station 203.

The secondary-cell addition request message may also be referred to as acell addition request message. The message may include identityinformation of the second cell, and is used to request the second basestation 203 to add the second cell as a cell communicating with theterminal 201.

S407. The second base station 203 sends a secondary-cell additionrequest acknowledgement message to the first base station 202.

The message may also be referred to as a cell addition requestacknowledgement message, and is used to indicate that the second basestation 203 allows addition of the second cell as a cell communicatingwith the terminal 201. The message may include information forperforming flow control between the second base station 203 and thefirst base station 202, configuration information for the terminal 201,and the like, for example, a wireless connection parameter that is usedto reconfigure the wireless connection between the terminal 201 and thesecond cell.

Alternatively, the terminal access indication message sent by the secondbase station 203 in step S405 includes indication information used toindicate that the second base station 203 allows addition of the secondcell as a cell communicating with the terminal 201. After receiving theterminal access indication message, the first base station 202 maydetermine, according to the indication information in the message, thatthe second base station 203 allows addition of the second cell as a cellcommunicating with the terminal 201. In addition, optionally, theterminal access indication message may include a wireless connectionparameter that is used to reconfigure the wireless connection betweenthe terminal 201 and the second cell. After obtaining the wirelessconnection parameter from the terminal access indication message, thefirst base station 202 performs step S408.

S408. The first base station 202 sends an RRC reconfiguration message tothe terminal 201.

The first base station 202 notifies, by using the message, the terminal201 that the second cell is to be added as a cell communicating with theterminal 201, for example, as a secondary cell for dual connectivity.

The message may include the wireless connection parameter obtained bythe first base station 202 in step S407. The terminal 201 reconfiguresthe wireless connection between the terminal 201 and the second cellaccording to the wireless connection parameter, and communicates withthe second cell by using the configured wireless connection.

S409. The terminal 201 sends an RRC reconfiguration complete message tothe first base station 202.

The terminal 201 obtains the wireless connection parameter from the RRCreconfiguration message sent by the first base station 202, and afterreconfiguring the wireless connection between the terminal 201 and thesecond cell according to the obtained wireless connection parameter,sends the RRC reconfiguration complete message to the first base station202. For example, after configuring the second cell as a secondary cellfor dual connectivity according to the obtained wireless connectionparameter, the terminal 201 sends the RRC reconfiguration completemessage to the first base station 202.

S410. The first base station 202 sends a secondary-cell additioncomplete message to the second base station 203.

The message may also be referred to as a cell addition complete message.After receiving the secondary-cell addition complete message sent by thefirst base station 202, the second base station 203 may determine thatthe terminal 201 has completed reconfiguration of the wirelessconnection between the terminal 201 and the second cell. The second basestation 203 may use the first base station 202 as a user plane anchor ofthe terminal 201. Data that is from the first base station 202 and is tobe sent to the terminal 201 is sent to the terminal 201 by using thesecond base station 203, or data that is from the terminal 201 isforwarded to the first base station 202.

In the first cell access solution and the second cell access solutionthat are provided in the embodiments of the present invention, the firstbase station 202 may be a macro base station or a small node, or thefirst base station 202 may include an access node of the first cell anda control plane anchor corresponding to the access node.

The second base station 203 may be a small node, a macro base station,or a Wireless Fidelity (Wireless Fidelity, WiFi) access point (AccessPoint, AP).

In the second cell access solution provided in this embodiment of thepresent invention, when the second cell is a WiFi AP, a cell accessprocedure may be shown in FIG. 5, and includes the following steps.

S501. A terminal 201 accesses, by using an RRC connection establishmentprocess, a first cell of a first base station 202.

This step is the same as step S401.

S502. The first base station 202 sends WiFi access assistanceinformation to the terminal 201.

The WiFi access assistance information may include a WiFi network ruleand/or an assistance parameter, for example, a received signal strengthindicator (RSSI for short) threshold, a list of WiFi APs that can beselected, and a preferred selection indication.

S503. The terminal 201 detects that a WiFi AP 203 can be used.

The terminal 201 may perform WiFi network access decision according tothe assistance parameter or the WiFi network rule or both that isobtained in advance in step S502, for example, an access networkdiscovery and selection function (Access Network Discovery and SelectionFunction, ANDSF) policy, and the decision includes decision about WiFiAP selection and/or which service is to be offloaded to a WiFi network.In this case, the WiFi AP 203 may be considered as the second basestation 203.

S504: The terminal 201 accesses a WiFi network by using a WiFi networkaccess process.

The access process may include a WiFi association (association) process,and in addition, may include a WiFi authentication process and an IPaddress allocation process.

Step S505 to step S510 may be respectively the same as step S405 to stepS410. Details are not described herein again.

A WiFi AP may also be replaced with a WiFi access controller (AccessController, AC), or may be replaced with an intermediate node connectedbetween a cellular network and a wireless local area network (WLAN forshort).

By using the first cell access solution and the second cell accesssolution that are provided in the embodiments of the present invention,a terminal 201 autonomously triggers a cell addition process, so as toimplement self-management on network access of the terminal 201.Therefore, network implementation is simplified, network costs arereduced, and a peak rate of a user is improved by using a carrieraggregation or dual connectivity technology.

Two cell access solutions provided in the embodiments of the presentinvention are described above. A data transmission solution provided inthe embodiments of the present invention is described in the following.

Data Transmission Solution

The data transmission solution provided in an embodiment of the presentinvention may be used, so that an application server can send an IPpacket to a terminal.

A terminal reports an address of the terminal to a location server. Thelocation server sends the received address of the terminal to anapplication server performing data transmission with the terminal, or anapplication server obtains the address of the terminal from the locationserver. The application server sends an IP packet to the terminalaccording to the obtained address of the terminal.

The data transmission solution provided in this embodiment of thepresent invention may be applied to a network architecture shown in FIG.6. The location server is located in a first server or a second server,or is an independent server, and is connected to an access anchor byusing an Internet. The access anchor may include a control plane anchorand/or a user plane anchor. The terminal may communicate with thelocation server by using an access node and the access anchor.Alternatively, when an access node and the access anchor are implementedin a base station, the terminal may directly communicate with thelocation server by using the base station. In this case, the basestation is connected to the location server by using the Internet.

The data transmission solution provided in this embodiment of thepresent invention is applicable to network architectures of variousradio access networks, provided that the terminal can report the addressof the terminal to the location server.

In a current LTE system, if an MME changes, or an MME does not include avalid context of UE, or an identity of an MME changes, the MME sends anupdate request message to an HSS, and the message includes a terminalidentity IMSI of the UE, the identity of the MME, and an update type.The HSS sends a location cancellation message to an old MME, and themessage includes the IMSI of the UE and a cancellation type. The old MMEdeletes a context of the terminal, and replies with an acknowledgementmessage. The HSS sends a location update message to a new MME, and themessage includes the IMSI of the UE and subscription data. It can belearned that in the current LTE system, because terminal locationinformation registered with the HSS is an identity of an MME in whichthe terminal is currently located, a location is not precise. Inaddition, because the terminal location information is reported by theMME, the UE cannot autonomously report the terminal locationinformation.

In this embodiment of the present invention, when an IP address of aterminal changes, the terminal can autonomously report the address to alocation server, so that a location is more precise. In addition,because control of another core network device such as an MME is notrequired, implementation is simpler.

A procedure of the data transmission solution provided in thisembodiment of the present invention may be shown in FIG. 7, and includesthe following steps.

S701. A terminal enables a new service.

S702. The terminal performs network search and network access.

The terminal may determine, according to at least one of a type of thenew service enabled in step S701, a QoS requirement of the new service,or a user network selection preference factor of a user corresponding tothe terminal, a network search sequence and a to-be-accessed networkthat is finally selected. For example, the terminal preferably accessesa WiFi network, and preferably searches for a WiFi network that can beused. After accessing a new network, the terminal usually obtains a newaddress such as an IP address.

S703. The terminal reports a current address to a location server, forexample, a new address obtained in step S702.

A scenario in which a third party wants to communicate with a designatedterminal by using an application server may exist. For example, aterminal B sends a WeChat call request to a terminal A by using a WeChatserver (which is a type of application server), and the WeChat serverneeds to find the terminal A. If there is cooperation and subscriptionbetween the WeChat server and an MNO server, the WeChat server can findan IP address of the terminal A by means of query by using a locationserver corresponding to the MNO server, and then communicate with theterminal A by using the IP address of the terminal A that is obtained bymeans of query.

Because there are various applications, there are also variouscorresponding application servers. For many applications in which dataexchange is only occasionally performed between the terminal and theapplication server, for example, various instant messaging (IM forshort) applications such as QQ, if the terminal reports, each time theIP address is updated, the IP address to application serverscorresponding to these applications, message overheads are relativelylarge. However, when the location server is used, the terminal mayreport the IP address of the terminal only to the location server, andthen notify the application server of the IP address by using thelocation server, so that processing overheads of the terminal arereduced, and occupation of air interface resources is reduced.

Particularly, for an application server that uses an MPTCP, because alarge amount of data is usually transmitted continuously, it isbeneficial to report the IP address of the terminal to the applicationserver in a timely manner, so that the application server can know ausable path (IP address) in a timely manner, offload data to the usablepath in a timely manner for transmission, and no longer offloads data toa non-usable path in a timely manner. Therefore, data transmissionefficiency is improved.

A manner in which the terminal reports the current address includes butis not limited to the following two manners.

Manner 1:

The terminal reports the current address by using control planesignaling.

If multiple data transmission paths exist between the terminal and theapplication server, for each of the data transmission paths, theterminal may report an address of the terminal on the path by using thecontrol plane signaling.

Manner 2:

The terminal sends an IP packet to the location server, uses a source IPaddress in the sent IP packet as the address of the terminal, andreports the address of the terminal to the location server.

If multiple data transmission paths exist between the terminal and theapplication server, for each of the multiple data transmission paths,the terminal sends an IP packet to the location server by using the datatransmission path, uses a source IP address in the sent IP packet as anaddress of the terminal on the data transmission path, and reports theaddress of the terminal to the location server.

For manner 1, the address reported by the terminal may include at leastone of the following addresses:

a public Internet Protocol IP address of the terminal,

an IP address of an access gateway to which the terminal is connected,or

an identity of an access gateway to which the terminal is connected.

The terminal accesses an Internet by using the access gateway to whichthe terminal is connected, and performs packet transmission with theapplication server in the Internet. The access gateway may be consideredas an entrance by which the terminal accesses the Internet.

Optionally, for a terminal that uses a dual connectivity or carrieraggregation technology, because a user plane anchor exists in a radioaccess network, and multiple connections or multiple carriers share asame IP address, the multiple connections or the multiple carriers maybe considered as one path instead of multiple paths between the terminaland the application server or the location server.

In addition, the application server may also be a multipath aggregationserver to which the application server is connected, for example, aserver that implements a Multipath Transmission Control Protocol (MPTCPfor short) function.

S704. The terminal searches for a new network, and accesses the network.

When some or all current paths cannot be used or cannot meet a servicerequirement, for example, channel quality or a data rate is lower than athreshold, the terminal triggers a network search and network accessprocess. Similarly, the terminal determines, according to at least oneof a type of a current service, a QoS requirement of a service, or auser network selection preference factor of a user corresponding to theterminal, a network search sequence and a to-be-accessed network that isfinally selected.

S705. The terminal reports a current address to the location server.

When a path to the application server or the location server is added ordeleted, the terminal may trigger a process of reporting the currentaddress. In addition, the terminal may periodically report the currentaddress of the terminal. For example, the terminal periodically sends aheartbeat packet.

Same as step S703, a manner in which the terminal reports the currentaddress also includes but is not limited to the manner 1 and the manner2.

Optionally, the location server receives the address of the terminalthat is reported by the terminal. The location server may activelynotify, the application server performing data transmission with theterminal, of the received address of the terminal. The applicationserver sends an IP packet to the terminal according to the receivedaddress of the terminal.

Alternatively, after receiving a request message that is sent by theapplication server and is for requesting the address of the terminal,the location server may notify, the application server performing datatransmission with the terminal, of the received address of the terminal.

Optionally, the terminal in the data transmission solution provided inthis embodiment of the present invention may be the terminal 201 in thewireless communications system shown in FIG. 2. A base station in FIG. 7may be the first base station 202 or the second base station 203, or maybe another base station in the wireless communications system.

By using the data transmission solution provided in this embodiment ofthe present invention, a terminal can periodically report an address ofthe terminal, or report an address of the terminal when a communicationspath between the terminal and an application server or a location serverchanges, so that the application server can send an IP packet to theterminal according to the obtained address of the terminal.

When the solution is applied to the network architecture shown in FIG.6, a mobility management function of the terminal in the networkarchitecture can be implemented. The terminal reports the address of theterminal to the location server, and then the location server notifiesthe application server of the received address of the terminal.Therefore, implementation is relatively simple, network design can besimplified, and network costs can be reduced.

The wireless communications system, the first cell access solution, thesecond cell access solution, and the data transmission solution that areprovided in the embodiments of the present invention are describedabove.

Based on a same invention concept, the embodiments of the presentinvention further provide a terminal, a first base station, a secondbase station, a location server, a cell access method, and a datatransmission method. Principles thereof for resolving technical problemsare similar to those of the foregoing solutions provided in theembodiments of the present invention. Therefore, for implementationthereof, refer to implementation of the foregoing solutions, and detailsare not repeated.

For example, based on a same invention concept as that of the first cellaccess solution provided in the embodiments of the present invention,the embodiments of the present invention further provide two terminals,two types of first base stations, and two cell access methods.Descriptions are separately provided in the following.

FIG. 8 is a schematic structural diagram of a first terminal accordingto an embodiment of the present invention. As shown in FIG. 8, theterminal includes: a transceiver module 801, configured to when theterminal needs to communicate with a second cell, send a first celladdition request message to a first base station of the first cell,where the first cell addition request message is used to request thefirst base station to add the second cell as a cell communicating withthe terminal, and a processing module 802, configured to afterreceiving, by using the transceiver module 80 i, a configuration messagethat is sent by the first base station and is used to configure awireless connection by which the terminal communicates with the secondcell, configure, according to the configuration message, the wirelessconnection by which the terminal communicates with the second cell, andcontrol the terminal to access the second cell by using the configuredwireless connection by which the terminal communicates with the secondcell.

Optionally, the processing module 802 is specifically configured toobtain, from the configuration message, a wireless connection parameterthat is used to configure the wireless connection by which the terminalcommunicates with the second cell, and configure, according to theobtained wireless connection parameter, the wireless connection by whichthe terminal communicates with the second cell.

Optionally, the transceiver module 801 is further configured to afterthe processing module 802 configures, according to the configurationmessage, the wireless connection by which the terminal communicates withthe second cell, and before the processing module 802 controls theterminal to access the second cell, send a first configuration completemessage to the first base station, so as to indicate to the first basestation that the terminal has completed, according to the configurationmessage, configuration of the wireless connection by which the terminalcommunicates with the second cell.

Optionally, the processing module 802 is further configured to beforethe transceiver module 80 i sends the first cell addition requestmessage, measure a wireless signal transmitted in the second cell, anddetermine, according to a measurement result of the measuring, that thesecond cell is available.

Optionally, the transceiver module 801 is further configured to beforethe processing module 802 measures the wireless signal transmitted inthe second cell, receive a measurement configuration message sent by thefirst base station, where the measurement configuration message includescell identity information of the second cell, and information about adecision condition used to determine whether the second cell isavailable.

The processing module 802 is specifically configured to measure,according to the cell identity information of the second cell that isincluded in the measurement configuration message, the wireless signaltransmitted in the second cell, and when the measurement result of themeasuring meets the decision condition, determine that the second cellis available.

Optionally, the transceiver module 801 is further configured to beforethe processing module 802 measures the wireless signal transmitted inthe second cell, receive a measurement configuration message sent by thefirst base station, where the measurement configuration message includesfrequency information of the second cell, and information about adecision condition used to determine whether the second cell isavailable.

The processing module 802 is specifically configured to measure,according to the frequency information of the second cell that isincluded in the measurement configuration message, the wireless signaltransmitted in the second cell, and when the measurement result of themeasuring meets the decision condition, determine that the second cellis available.

Optionally, the transceiver module 801 is further configured to beforethe processing module 802 measures the wireless signal transmitted inthe second cell, receive a first indication message sent by the firstbase station or a second base station of the second cell.

The processing module 802 is further configured to determine, accordingto the first indication message, that the second cell may be added as acell communicating with the terminal, where the first indication messageis used to indicate that the second cell may provide communication for asame terminal together with the first cell.

Optionally, the first base station is a macro base station or a smallnode, or the first base station includes an access node of the firstcell and a control plane anchor corresponding to the access node. Theaccess node keeps a wireless connection to the terminal. The controlplane anchor is configured to control the terminal to establish awireless connection to the access node, and enable, by exchanginginformation with a second server, the second server to perform userinformation management on the terminal. The second server is configuredto perform user information management on the terminal.

The second base station of the second cell is a small node, a macro basestation, or a Wireless Fidelity WiFi access point AP.

For another optional implementation of the terminal, refer toimplementation of the terminal 201 in the first cell access method, anddetails are not repeated.

FIG. 9 is a schematic structural diagram of a second terminal accordingto an embodiment of the present invention. As shown in FIG. 9, theterminal includes a transceiver 901, configured to when the terminalneeds to communicate with a second cell, send a first cell additionrequest message to a first base station of the first cell, where thefirst cell addition request message is used to request the first basestation to add the second cell as a cell communicating with theterminal, and a processor 902, configured to after receiving, by usingthe transceiver 901, a configuration message that is sent by the firstbase station and is used to configure a wireless connection by which theterminal communicates with the second cell, configure, according to theconfiguration message, the wireless connection by which the terminalcommunicates with the second cell, and control the terminal to accessthe second cell by using the configured wireless connection by which theterminal communicates with the second cell.

Optionally, the terminal may be implemented by using a bus architectureshown in FIG. 9. In FIG. 9, the bus architecture may include anyquantity of interconnected buses and bridges, and specifically linkvarious circuits of one or more processors represented by the processor902 and a memory. The bus architecture may further link various othercircuits such as a peripheral device, a voltage regulator, and a powermanagement circuit. This is well known in the art, and therefore, is notfurther described in this specification. A bus interface provides aninterface. The transceiver 901 may be multiple elements, that is, mayinclude a transmitter and a receiver, and provide units forcommunicating with various other apparatuses on a transmission medium.For different user equipments, a user interface may be an interface thatcan be externally or internally connected to a required device. Theconnected device includes but is not limited to a keypad, a display, aloudspeaker, a microphone, and a joystick.

Optionally, the terminal may be implemented without using a busarchitecture. For example, the processor 902 and the transceiver 901 aredirectly connected to each other, and do not communicate with each otherby using a bus.

For implementation of the transceiver 901, refer to the transceivermodule 801. For implementation of the processor 902, refer to theprocessing module 802. For another optional implementation of theterminal, refer to implementation of the terminal 201 in the first cellaccess solution provided in the embodiments of the present invention,and details are not repeated.

FIG. 10 is a schematic structural diagram of a first type of first basestation according to an embodiment of the present invention. As shown inFIG. 10, the first base station includes: a transceiver module 1001,configured to receive a first cell addition request message sent by aterminal communicating with a first cell of the first base station,where the first cell addition request message is used to request thefirst base station to add a second cell as a cell communicating with theterminal, and a processing module 1002, configured to control thetransceiver module 1001 to send, to the terminal, a configurationmessage that is used to configure a wireless connection by which theterminal communicates with the second cell, so as to instruct theterminal to configure, according to the configuration message, thewireless connection by which the terminal communicates with the secondcell, and access the second cell.

Optionally, the transceiver module 1001 is further configured to afterreceiving the first cell addition request message, and before sending,to the terminal, the configuration message that is used to configure thewireless connection by which the terminal communicates with the secondcell, send a second cell addition request message to a second basestation of the second cell, so as to request to add the second cell as acell communicating with the terminal.

The processing module 1002 is specifically configured to control thetransceiver module 1001 to receive a cell addition requestacknowledgement message sent by the second base station in response tothe second cell addition request message, obtain, from the cell additionrequest acknowledgement message, a wireless connection parameter that isused to configure the wireless connection by which the terminalcommunicates with the second cell, and control the transceiver module1001 to send the configuration message to the terminal, where theconfiguration message carries the obtained wireless connectionparameter, so as to instruct the terminal to configure, according to thewireless connection parameter, the wireless connection by which theterminal communicates with the second cell, and access the second cell.

Optionally, the processing module 1002 is further configured to aftercontrolling the transceiver module 1001 to send the configurationmessage to the terminal, and after the transceiver module 1001 receivesa first configuration complete message sent by the terminal in responseto the configuration message, control the transceiver module 1001 tosend a second configuration complete message to the second base station,so as to indicate the second base station that the terminal hascompleted configuration of the wireless connection by which the terminalcommunicates with the second cell.

The first configuration complete message is used to indicate the firstbase station that the terminal has completed, according to theconfiguration message, configuration of the wireless connection by whichthe terminal communicates with the second cell.

Optionally, the processing module 1002 is further configured to beforethe transceiver module 1001 receives the first cell addition requestmessage sent by the terminal, control the transceiver module 1001 tosend a measurement configuration message to the terminal, where themeasurement configuration message includes cell identity information ofthe second cell, and information about a decision condition used todetermine whether the second cell is available.

The first cell addition request message is sent by the terminal to thefirst base station after the terminal measures the second cell accordingto the cell identity information of the second cell in the measurementconfiguration message, and a measurement result obtained by measuringthe second cell meets the decision condition.

Optionally, the processing module 1002 is further configured to beforethe transceiver module 1001 receives the first cell addition requestmessage sent by the terminal, control the transceiver module 1001 tosend a measurement configuration message to the terminal, where themeasurement configuration message includes frequency information of thesecond cell, and information about a decision condition used todetermine whether the second cell is available.

The first cell addition request message is sent by the terminal to thefirst base station after the terminal measures the second cell accordingto the frequency information of the second cell in the measurementconfiguration message, and a measurement result obtained by measuringthe second cell meets the decision condition.

Optionally, the processing module 1002 is further configured to beforecontrolling the transceiver module 1001 to send the measurementconfiguration message to the terminal, control the transceiver module1001 to send a first indication message to the terminal, so as toindicate the terminal, and the second cell may provide communication fora same terminal together with the first cell.

Optionally, the first base station is a macro base station or a smallnode, or the first base station includes a first node of the first celland a first control node configured to control the first node. The firstnode is configured to process transmission between the terminal and thefirst control node.

The base station of the second cell is a small node, a macro basestation, or a Wireless Fidelity WiFi access point AP.

For another optional implementation of the first base station, refer toimplementation of the first base station 202 in the first cell accesssolution provided in the embodiments of the present invention, anddetails are not repeated.

FIG. 11 is a schematic structural diagram of a second type of first basestation according to an embodiment of the present invention. As shown inFIG. 1i , the first base station includes: a transceiver 1101,configured to receive a first cell addition request message sent by aterminal communicating with a first cell of the first base station,where the first cell addition request message is used to request thefirst base station to add a second cell as a cell communicating with theterminal, and a processor 1102, configured to control the transceiver1101 to send, to the terminal, a configuration message that is used toconfigure a wireless connection by which the terminal communicates withthe second cell, so as to instruct the terminal to configure, accordingto the configuration message, the wireless connection by which theterminal communicates with the second cell, and access the second cell.

Optionally, the terminal may be implemented by using a bus architectureshown in FIG. 11. In FIG. 1i , the bus architecture may include anyquantity of interconnected buses and bridges, and specifically linkvarious circuits of one or more processors represented by the processor1102 and a memory. The bus architecture may further link various othercircuits such as a peripheral device, a voltage regulator, and a powermanagement circuit. This is well known in the art, and therefore, is notfurther described in this specification. A bus interface provides aninterface. The transceiver 1101 may be multiple elements, that is, mayinclude a transmitter and a receiver, and provide units forcommunicating with various other apparatuses on a transmission medium.For different user equipments, a user interface may be an interface thatcan be externally or internally connected to a required device. Theconnected device includes but is not limited to a keypad, a display, aloudspeaker, a microphone, and a joystick.

Optionally, the terminal may be implemented without using a busarchitecture. For example, the processor 1102 and the transceiver 1101are directly connected to each other, and do not communicate with eachother by using a bus.

For another optional implementation of the transceiver 1101, refer tothe transceiver module 1001. For another optional implementation of theprocessor 1102, refer to the processing module 1002. For anotheroptional implementation of the terminal, refer to implementation of thefirst base station 202 in the first cell access solution provided in theembodiments of the present invention, and details are not repeated.

FIG. 12 is a flowchart of a first cell access method according to anembodiment of the present invention. As shown in FIG. 12, the methodincludes the following steps.

S1201. When a terminal communicating with a first cell needs tocommunicate with a second cell, the terminal sends a first cell additionrequest message to a first base station of the first cell, where thefirst cell addition request message is used to request the first basestation to add the second cell as a cell communicating with theterminal.

S1202. After receiving a configuration message that is sent by the firstbase station and is used to configure a wireless connection by which theterminal communicates with the second cell, the terminal configures,according to the configuration message, the wireless connection by whichthe terminal communicates with the second cell.

S1203. The terminal accesses the second cell by using the configuredwireless connection by which the terminal communicates with the secondcell.

Optionally, the configuring, by the terminal according to theconfiguration message, the wireless connection by which the terminalcommunicates with the second cell includes: obtaining, by the terminalfrom the configuration message, a wireless connection parameter that isused to configure the wireless connection by which the terminalcommunicates with the second cell, and configuring, by the terminalaccording to the obtained wireless connection parameter, the wirelessconnection by which the terminal communicates with the second cell.

Optionally, after the terminal configures, according to theconfiguration message, the wireless connection by which the terminalcommunicates with the second cell, and before the terminal accesses thesecond cell, the method further includes: sending, by the terminal, afirst configuration complete message to the first base station, so as toindicate to the first base station that the terminal has completed,according to the configuration message, configuration of the wirelessconnection by which the terminal communicates with the second cell.

Optionally, before the terminal sends the first cell addition requestmessage, the method further includes measuring, by the terminal, awireless signal transmitted in the second cell, and determining,according to a measurement result of the measuring, that the second cellis available.

Optionally, before the measuring, by the terminal, a wireless signaltransmitted in the second cell, the method further includes receiving,by the terminal, a measurement configuration message sent by the firstbase station, where the measurement configuration message includes cellidentity information of the second cell, and information about adecision condition used to determine whether the second cell isavailable.

The measuring, by the terminal, a wireless signal transmitted in thesecond cell, and determining, according to a measurement result of themeasuring, that the second cell is available includes measuring, by theterminal according to the cell identity information of the second cellthat is included in the measurement configuration message, the wirelesssignal transmitted in the second cell, and when the measurement resultof the measuring meets the decision condition, determining that thesecond cell is available.

Optionally, before the measuring, by the terminal, a wireless signaltransmitted in the second cell, the method further includes receiving,by the terminal, a measurement configuration message sent by the firstbase station, where the measurement configuration message includesfrequency information of the second cell, and information about adecision condition used to determine whether the second cell isavailable.

The measuring, by the terminal, a wireless signal transmitted in thesecond cell, and determining, according to a measurement result of themeasuring, that the second cell is available includes measuring, by theterminal according to the frequency information of the second cell thatis included in the measurement configuration message, the wirelesssignal transmitted in the second cell, and when the measurement resultof the measuring meets the decision condition, determining that thesecond cell is available.

Optionally, before the measuring, by the terminal, a wireless signaltransmitted in the second cell, the method further includes receiving,by the terminal, a first indication message sent by the first basestation or a second base station of the second cell, and determining, bythe terminal according to the first indication message, that the secondcell may be added as a cell communicating with the terminal, where thefirst indication message is used to indicate that the second cell mayprovide communication for a same terminal together with the first cell.

Optionally, the first base station is a macro base station or a smallnode, or the first base station includes an access node of the firstcell and a control plane anchor corresponding to the access node. Theaccess node keeps a wireless connection to the terminal. The controlplane anchor is configured to control the terminal to establish awireless connection to the access node, and enable, by exchanginginformation with a second server, the second server to perform userinformation management on the terminal. The second server is configuredto perform user information management on the terminal.

The second base station of the second cell is a small node, a macro basestation, or a Wireless Fidelity WiFi access point AP.

For another optional implementation of the cell access method, refer toimplementation of the terminal 201 in the first cell access solution,and details are not repeated.

FIG. 13 is a flowchart of a second cell access method according to anembodiment of the present invention. As shown in FIG. 13, the methodincludes the following steps.

S1301. A first base station of a first cell receives a first celladdition request message sent by a terminal communicating with the firstcell, where the first cell addition request message is used to requestthe first base station to add a second cell as a cell communicating withthe terminal.

S1302. The first base station sends, to the terminal, a configurationmessage that is used to configure a wireless connection by which theterminal communicates with the second cell, so as to instruct theterminal to configure, according to the configuration message, thewireless connection by which the terminal communicates with the secondcell, and access the second cell.

Optionally, after the first base station receives the first celladdition request message, and before the first base station sends, tothe terminal, the configuration message that is used to configure thewireless connection by which the terminal communicates with the secondcell, the method further includes: sending, by the first base station, asecond cell addition request message to a second base station of thesecond cell, so as to request to add the second cell as a cellcommunicating with the terminal.

The sending, by the first base station to the terminal, a configurationmessage that is used to configure a wireless connection by which theterminal communicates with the second cell, so as to instruct theterminal to configure, according to the configuration message, thewireless connection by which the terminal communicates with the secondcell, and access the second cell includes receiving, by the first basestation, a cell addition request acknowledgement message sent by thesecond base station in response to the second cell addition requestmessage, obtaining, by the first base station from the cell additionrequest acknowledgement message, a wireless connection parameter that isused to configure the wireless connection by which the terminalcommunicates with the second cell, and sending, by the first basestation, the configuration message to the terminal, where theconfiguration message carries the obtained wireless connectionparameter, so as to instruct the terminal to configure, according to thewireless connection parameter, the wireless connection by which theterminal communicates with the second cell, and access the second cell.

Optionally, after the first base station sends the configuration messageto the terminal, the method further includes receiving, by the firstbase station, a first configuration complete message sent by theterminal in response to the configuration message, where the firstconfiguration complete message is used to indicate the first basestation that the terminal has completed, according to the configurationmessage, configuration of the wireless connection by which the terminalcommunicates with the second cell, and after receiving the configurationcomplete message, sending, by the first base station, a secondconfiguration complete message to the second base station, so as toindicate the second base station that the terminal has completedconfiguration of the wireless connection by which the terminalcommunicates with the second cell.

Optionally, before the first base station receives the first celladdition request message sent by the terminal, the method furtherincludes sending, by the first base station, a measurement configurationmessage to the terminal, where the measurement configuration messageincludes cell identity information of the second cell, and informationabout a decision condition used to determine whether the second cell isavailable.

The first cell addition request message is sent by the terminal to thefirst base station after the terminal measures the second cell accordingto the cell identity information of the second cell in the measurementconfiguration message, and a measurement result obtained by measuringthe second cell meets the decision condition.

Optionally, before the first base station receives the first celladdition request message sent by the terminal, the method furtherincludes sending, by the first base station, a measurement configurationmessage to the terminal, where the measurement configuration messageincludes frequency information of the second cell, and information abouta decision condition used to determine whether the second cell isavailable.

The first cell addition request message is sent by the terminal to thefirst base station after the terminal measures the second cell accordingto the frequency information of the second cell in the measurementconfiguration message, and a measurement result obtained by measuringthe second cell meets the decision condition.

Optionally, before the first base station sends the measurementconfiguration message to the terminal, the method further includessending, by the first base station, a first indication message to theterminal, so as to indicate the terminal that the second cell mayprovide communication for a same terminal together with the first cell.

Optionally, the first base station is a macro base station or a smallnode, or the first base station includes a first node of the first celland a first control node configured to control the first node. The firstnode is configured to process transmission between the terminal and thefirst control node.

The base station of the second cell is a small node, a macro basestation, or a Wireless Fidelity WiFi access point AP.

For another optional implementation of the method, refer to processingof the first base station 202 in the first cell access solution, anddetails are not repeated.

FIG. 14 is a schematic structural diagram of a third terminal accordingto an embodiment of the present invention. The terminal communicateswith a first cell. As shown in FIG. 14, the terminal includes: aprocessing module 1402, configured to when the terminal needs tocommunicate with a second cell, initiate a connection establishmentprocess, establish, by using the connection establishment process, awireless connection by which the terminal communicates with the secondcell, and control the terminal to access the second cell by using theestablished wireless connection, and a transceiver module 1401,configured to receive a reconfiguration message sent by a first basestation of the first cell.

The processing module 1402 is further configured to after thetransceiver module 1401 receives the reconfiguration message,reconfigure the wireless connection according to the reconfigurationmessage, and control the terminal to communicate with the second cell byusing the reconfigured wireless connection.

The reconfiguration message is sent by the first base station to theterminal after the first base station determines, according to aterminal access indication message that is received from a second basestation of the second cell and is used to indicate that the terminalaccesses the second cell, that the terminal accesses the second cell,and after the first base station determines that the second base stationallows addition of the second cell as a cell communicating with theterminal.

Optionally, the processing module 1402 is further configured to afterreconfiguring the wireless connection according to the reconfigurationmessage, and before controlling the terminal to communicate with thesecond cell by using the reconfigured wireless connection, control thetransceiver module 1401 to send a reconfiguration complete message tothe first base station, so as to indicate to the first base station thatthe terminal has completed reconfiguration of the wireless connectionaccording to the reconfiguration message.

Optionally, the processing module 1402 is further configured to beforecontrolling the terminal to establish the wireless connection to thesecond cell, measure a wireless signal transmitted in the second cell,and determine, according to a measurement result of the measuring, thatthe second cell is available.

Optionally, the transceiver module 1401 is further configured to beforethe processing module 1402 measures the wireless signal transmitted inthe second cell, receive a measurement configuration message sent by thefirst base station, where the measurement configuration message includescell identity information of the second cell, and information about adecision condition used to determine whether the second cell isavailable.

The processing module 1402 is specifically configured to measure,according to the cell identity information of the second cell that isincluded in the measurement configuration message, the wireless signaltransmitted in the second cell, and when the measurement result of themeasuring meets the decision condition, determine that the second cellis available.

Optionally, the transceiver module 1401 is further configured to beforethe processing module 1402 measures the wireless signal transmitted inthe second cell, receive a measurement configuration message sent by thefirst base station, where the measurement configuration message includesfrequency information of the second cell, and information about adecision condition used to determine whether the second cell isavailable.

The processing module 1402 is specifically configured to measure,according to the frequency information of the second cell that isincluded in the measurement configuration message, the wireless signaltransmitted in the second cell, and when the measurement result of themeasuring meets the decision condition, determine that the second cellis available.

Optionally, the transceiver module 1401 is further configured to beforethe processing module 1402 measures the wireless signal transmitted inthe second cell, receive a first indication message sent by the secondbase station or the first base station.

The processing module 1402 is further configured to determine, accordingto the first indication message, that the second cell may be added as acell communicating with the terminal, where the first indication messageis used to indicate that the second cell may provide communication for asame terminal together with the first cell.

Optionally, the first base station is a macro base station or a smallnode, or the first base station includes a first node of the first celland a first control node configured to control the first node. The firstnode is configured to process transmission between the terminal and thefirst control node.

The second base station is a small node, a macro base station, or aWireless Fidelity WiFi access point AP.

For another optional implementation of the terminal, refer toimplementation of the terminal 201 in the second cell access solutionprovided in the embodiments of the present invention, and details arenot repeated.

FIG. 15 is a schematic structural diagram of a fourth terminal accordingto an embodiment of the present invention. The terminal communicateswith a first cell. As shown in FIG. 15, the terminal includes: aprocessor 1502, configured to when the terminal needs to communicatewith a second cell, initiate a connection establishment process,establish, by using the connection establishment process, a wirelessconnection by which the terminal communicates with the second cell, andcontrol the terminal to access the second cell by using the establishedwireless connection, and a transceiver 1501, configured to receive areconfiguration message sent by a first base station of the first cell.

The processor 1502 is further configured to after the transceiver 1501receives the reconfiguration message, reconfigure the wirelessconnection according to the reconfiguration message, and control theterminal to communicate with the second cell by using the reconfiguredwireless connection.

The reconfiguration message is sent by the first base station to theterminal after the first base station determines, according to aterminal access indication message that is received from a second basestation of the second cell and is used to indicate that the terminalaccesses the second cell, that the terminal accesses the second cell,and after the first base station determines that the second base stationallows addition of the second cell as a cell communicating with theterminal.

Optionally, the terminal may be implemented by using a bus architectureshown in FIG. 15. In FIG. 15, the bus architecture may include anyquantity of interconnected buses and bridges, and specifically linkvarious circuits of one or more processors represented by the processor1502 and a memory. The bus architecture may further link various othercircuits such as a peripheral device, a voltage regulator, and a powermanagement circuit. This is well known in the art, and therefore, is notfurther described in this specification. A bus interface provides aninterface. The transceiver 1501 may be multiple elements, that is, mayinclude a transmitter and a receiver, and provide units forcommunicating with various other apparatuses on a transmission medium.For different user equipments, a user interface may be an interface thatcan be externally or internally connected to a required device. Theconnected device includes but is not limited to a keypad, a display, aloudspeaker, a microphone, and a joystick.

Optionally, the terminal may be implemented without using a busarchitecture. For example, the processor 1502 and the transceiver 1501are directly connected to each other, and do not communicate with eachother by using a bus.

For another optional implementation of the transceiver 1501, refer tothe transceiver module 1401. For another optional implementation of theprocessor 1502, refer to the processing module 1402. For anotheroptional implementation of the terminal, refer to implementation of theterminal 201 in the second cell access solution provided in theembodiments of the present invention, and details are not repeated.

FIG. 16 is a schematic structural diagram of a third type of first basestation according to an embodiment of the present invention. As shown inFIG. 16, the first base station includes a transceiver module 1601,configured to receive a terminal access indication message that is sentby a second base station of a second cell and is used to indicate that aterminal communicating with a first cell of the first base stationaccesses the second cell, and a processing module 1602, configured toafter the transceiver module 1601 receives the terminal accessindication message, and if determining that the second base stationallows addition of the second cell as a cell communicating with theterminal, control the transceiver module 1601 to send a reconfigurationmessage to the terminal, so as to instruct the terminal to reconfigure,according to the reconfiguration message, a wireless connectionestablished when the terminal accesses the second cell, and communicatewith the second cell by using the configured wireless connection.

Optionally, the terminal access indication message is further used toindicate that the second base station allows addition of the second cellas a cell communicating with the terminal.

The processing module 1602 is specifically configured to after thetransceiver module 1601 receives the terminal access indication message,determine that the second base station allows addition of the secondcell as a cell communicating with the terminal.

Optionally, the terminal access indication message carries a wirelessconnection parameter that is used to reconfigure the wirelessconnection.

The processing module 1602 is specifically configured to add, to thereconfiguration message, the wireless connection parameter obtained fromthe terminal access indication message, and send the reconfigurationmessage to the terminal by using the transceiver module 1601.

The reconfiguration message is specifically used to instruct theterminal to reconfigure the wireless connection according to thewireless connection parameter, and communicate with the second cell byusing the configured wireless connection.

Optionally, the processing module 1602 is further configured to afterthe transceiver module 1601 receives the terminal access indicationmessage, control the transceiver module 1601 to send a cell additionrequest message to the second base station, so as to request the secondbase station to add the second cell as a cell communicating with theterminal.

The processing module 1602 is specifically configured to after thetransceiver module 1601 receives a cell addition request acknowledgementmessage sent by the second base station in response to the cell additionrequest message, determine that the second base station allows additionof the second cell as a cell communicating with the terminal.

Optionally, the cell addition request acknowledgement message carries awireless connection parameter that is used to reconfigure the wirelessconnection.

The processing module 1602 is specifically configured to add, to thereconfiguration message, the wireless connection parameter obtained fromthe cell addition request acknowledgement message, and send thereconfiguration message to the terminal by using the transceiver module1601.

The reconfiguration message is specifically used to instruct theterminal to reconfigure the wireless connection according to thewireless connection parameter, and communicate with the second cell byusing the configured wireless connection.

Optionally, the transceiver module 1601 is further configured to aftersending the reconfiguration message to the terminal, receive areconfiguration complete message sent by the terminal in response to thereconfiguration message.

The processing module 1602 is further configured to determine, accordingto the reconfiguration complete message, that the terminal has completedreconfiguration of the wireless connection according to thereconfiguration message, and control the transceiver module 1601 to senda cell addition complete message to the second base station, so as toindicate the second base station that the terminal has completedreconfiguration of the wireless connection.

Optionally, the processing module 1602 is further configured to beforethe transceiver module 1601 receives the terminal access indicationmessage, control the transceiver module 1601 to send a measurementconfiguration message to the terminal, where the measurementconfiguration message includes cell identity information of the secondcell, and information about a decision condition used to determinewhether the second cell is available, so as to instruct the terminal tomeasure, according to the cell identity information of the second cellthat is included in the measurement configuration message, a wirelesssignal transmitted in the second cell, and when a measurement result ofthe measuring meets the decision condition, determine that the secondcell is available.

Optionally, the processing module 1602 is further configured to beforethe transceiver module 1601 receives the terminal access indicationmessage, control the transceiver module 1601 to send a measurementconfiguration message to the terminal, where the measurementconfiguration message includes frequency information of the second cell,and information about a decision condition used to determine whether thesecond cell is available, so as to instruct the terminal to measure,according to the frequency information of the second cell that isincluded in the measurement configuration message, a wireless signaltransmitted in the second cell, and when a measurement result of themeasuring meets the decision condition, determine that the second cellis available.

Optionally, the processing module 1602 is further configured to beforecontrolling the transceiver module 1601 to send the measurementconfiguration message, control the transceiver module 1601 to send afirst indication message to the terminal, where the first indicationmessage is used to indicate that the second cell may providecommunication for a same terminal together with the first cell.

Optionally, the first base station is a macro base station or a smallnode, or the first base station includes a first node of the first celland a first control node configured to control the first node. The firstnode is configured to process transmission between the terminal and thefirst control node.

The second base station is a small node, a macro base station, or aWireless Fidelity WiFi access point AP.

For another optional implementation of the first base station, refer toimplementation of the first base station 202 in the second cell accesssolution provided in the embodiments of the present invention, anddetails are not repeated.

FIG. 17 is a schematic structural diagram of a fourth type of first basestation according to an embodiment of the present invention. As shown inFIG. 17, the first base station includes a transceiver 1701, configuredto receive a terminal access indication message that is sent by a secondbase station of a second cell and is used to indicate that a terminalcommunicating with a first cell of the first base station accesses thesecond cell, and a processor 1702, configured to after the transceiver1701 receives the terminal access indication message, and if determiningthat the second base station allows addition of the second cell as acell communicating with the terminal, control the transceiver 1701 tosend a reconfiguration message to the terminal, so as to instruct theterminal to reconfigure, according to the reconfiguration message, awireless connection established when the terminal accesses the secondcell, and communicate with the second cell by using the configuredwireless connection.

Optionally, the terminal may be implemented by using a bus architectureshown in FIG. 17. In FIG. 17, the bus architecture may include anyquantity of interconnected buses and bridges, and specifically linkvarious circuits of one or more processors represented by the processor1702 and a memory. The bus architecture may further link various othercircuits such as a peripheral device, a voltage regulator, and a powermanagement circuit. This is well known in the art, and therefore, is notfurther described in this specification. A bus interface provides aninterface. The transceiver 1701 may be multiple elements, that is, mayinclude a transmitter and a receiver, and provide units forcommunicating with various other apparatuses on a transmission medium.For different user equipments, a user interface may be an interface thatcan be externally or internally connected to a required device. Theconnected device includes but is not limited to a keypad, a display, aloudspeaker, a microphone, and a joystick.

Optionally, the terminal may be implemented without using a busarchitecture. For example, the processor 1702 and the transceiver 1701are directly connected to each other, and do not communicate with eachother by using a bus.

For implementation of the transceiver 1701, refer to the transceivermodule 1601. For implementation of the processor 1702, refer to theprocessing module 1602. For another optional implementation of theterminal, refer to implementation of the first base station 202 in thesecond cell access solution provided in the embodiments of the presentinvention, and details are not repeated.

FIG. 18 is a schematic structural diagram of a first type of second basestation according to an embodiment of the present invention. As shown inFIG. 18, the second base station includes a processing module 1802 and atransceiver module 1801.

The processing module 1802 is configured to establish a wirelessconnection between a terminal and a second cell of the second basestation in a connection establishment process initiated by the terminal,and allow the terminal to access the second cell by using the wirelessconnection.

The processing module 1802 is further configured to after the terminalaccesses the second cell, control the transceiver module 1801 to send aterminal access indication message to a first base station of a firstcell communicating with the terminal, so as to indicate that the secondcell needs to be added, for the terminal, as a cell communicating withthe terminal.

Optionally, the terminal access indication message is further used toindicate that the second base station allows addition of the second cellas a cell communicating with the terminal.

The processing module 1802 is specifically configured to add, to theterminal access indication message, a wireless connection parameter thatis used to reconfigure the wireless connection, so as to instruct thefirst base station to instruct the terminal to reconfigure the wirelessconnection according to the wireless connection parameter.

Optionally, the transceiver module 1801 is further configured to aftersending the terminal access indication message to the first basestation, receive a cell addition complete message sent by the first basestation.

The processing module 1802 is further configured to after thetransceiver module 1801 receives the cell addition complete message,control the transceiver module 1801 to communicate with the terminal byusing the reconfigured wireless connection.

Optionally, the transceiver module 1801 is further configured to aftersending the terminal access indication message to the first basestation, receive a cell addition request message sent by the first basestation, where the cell addition request message is used to request thesecond base station to add the second cell as a cell communicating withthe terminal.

The processing module 1802 is further configured to control thetransceiver module 1801 to send a cell addition request acknowledgementmessage to the first base station in response to the cell additionrequest message, so as to indicate that the second base station allowsaddition of the second cell as a cell communicating with the terminal,where the cell addition request acknowledgement message carries awireless connection parameter that is used to reconfigure the wirelessconnection, so as to instruct the first base station to instruct theterminal to reconfigure the wireless connection according to thewireless connection parameter.

Optionally, the transceiver module 1801 is further configured to aftersending the cell addition request acknowledgement message to the firstbase station, receive a cell addition complete message sent by the firstbase station.

The processing module 1802 is further configured to after thetransceiver module 1801 receives the cell addition complete message,control the transceiver module 1801 to communicate with the terminal byusing the reconfigured wireless connection.

Optionally, the processing module 1802 is further configured to beforeestablishing the wireless connection between the terminal and the secondcell, control the transceiver module 1801 to send a first indicationmessage to the terminal, so as to indicate that the second cell mayprovide communication for a same terminal together with the first cell.

The connection establishment process initiated by the terminal isinitiated by the terminal after the terminal receives the firstindication message and determines, according to the first indicationmessage, that the first cell may provide communication for the terminaltogether with the first cell.

Optionally, the first base station is a macro base station or a smallnode, or the first base station includes a first node of the first celland a first control node configured to control the first node. The firstnode is configured to process transmission between the terminal and thefirst control node.

The second base station is a small node, a macro base station, or aWireless Fidelity WiFi access point AP.

For another optional implementation of the second base station, refer toimplementation of the second base station 203 in the second cell accesssolution provided in the embodiments of the present invention, anddetails are not repeated.

FIG. 19 is a schematic structural diagram of a second type of secondbase station according to an embodiment of the present invention. Asshown in FIG. 19, the second base station includes a processor 1902 anda transceiver 1901.

The processor 1902 is configured to establish a wireless connectionbetween a terminal and a second cell of the second base station in aconnection establishment process initiated by the terminal, and allowthe terminal to access the second cell by using the wireless connection.

The processor 1902 is further configured to after the terminal accessesthe second cell, control the transceiver 1901 to send a terminal accessindication message to a first base station of a first cell communicatingwith the terminal, so as to indicate that the second cell needs to beadded, for the terminal, as a cell communicating with the terminal.

Optionally, the second base station may be implemented by using a busarchitecture shown in FIG. 19. In FIG. 19, the bus architecture mayinclude any quantity of interconnected buses and bridges, andspecifically link various circuits of one or more processors representedby the processor 1902 and a memory. The bus architecture may furtherlink various other circuits such as a peripheral device, a voltageregulator, and a power management circuit. This is well known in theart, and therefore, is not further described in this specification. Abus interface provides an interface. The transceiver 1901 may bemultiple elements, that is, may include a transmitter and a receiver,and provide units for communicating with various other apparatuses on atransmission medium. For different user equipments, a user interface maybe an interface that can be externally or internally connected to arequired device. The connected device includes but is not limited to akeypad, a display, a loudspeaker, a microphone, and a joystick.

Optionally, the second base station may be implemented without using abus architecture. For example, the processor 1902 and the transceiver1901 are directly connected to each other, and do not communicate witheach other by using a bus.

For implementation of the transceiver 1901, refer to the transceivermodule 1801. For implementation of the processor 1902, refer to theprocessing module 1802. For another optional implementation of thesecond base station, refer to implementation of the second base station203 in the second cell access solution provided in the embodiments ofthe present invention, and details are not repeated.

FIG. 20 is a flowchart of a third cell access method according to anembodiment of the present invention. As shown in FIG. 20, the methodincludes the following steps.

S2001. When a terminal communicating with a first cell needs tocommunicate with a second cell, the terminal initiates a connectionestablishment process, establishes, by using the connectionestablishment process, a wireless connection by which the terminalcommunicates with the second cell, and accesses the second cell by usingthe established wireless connection.

S2002. After receiving a reconfiguration message sent by a first basestation of the first cell, the terminal reconfigures the wirelessconnection according to the reconfiguration message, and communicateswith the second cell by using the reconfigured wireless connection.

The reconfiguration message is sent by the first base station to theterminal after the first base station determines, according to aterminal access indication message that is received from a second basestation of the second cell and is used to indicate that the terminalaccesses the second cell, that the terminal accesses the second cell,and after the first base station determines that the second base stationallows addition of the second cell as a cell communicating with theterminal.

Optionally, after the terminal reconfigures the wireless connectionaccording to the reconfiguration message, and before the terminalcommunicates with the second cell by using the reconfigured wirelessconnection, the method further includes: sending, by the terminal, areconfiguration complete message to the first base station, so as toindicate to the first base station that the terminal has completedreconfiguration of the wireless connection according to thereconfiguration message.

Optionally, before the terminal establishes the wireless connection tothe second cell, the method further includes measuring, by the terminal,a wireless signal transmitted in the second cell, and determining,according to a measurement result of the measuring, that the second cellis available.

Optionally, before the measuring, by the terminal, a wireless signaltransmitted in the second cell, the method further includes receiving,by the terminal, a measurement configuration message sent by the firstbase station, where the measurement configuration message includes cellidentity information of the second cell, and information about adecision condition used to determine whether the second cell isavailable.

The measuring, by the terminal, a wireless signal sent in the secondcell, and determining, according to a measurement result of themeasuring, that the second cell is available includes measuring, by theterminal according to the cell identity information of the second cellthat is included in the measurement configuration message, the wirelesssignal transmitted in the second cell, and when the measurement resultof the measuring meets the decision condition, determining that thesecond cell is available.

Optionally, before the measuring, by the terminal, a wireless signaltransmitted in the second cell, the method further includes receiving,by the terminal, a measurement configuration message sent by the firstbase station, where the measurement configuration message includesfrequency information of the second cell, and information about adecision condition used to determine whether the second cell isavailable.

The measuring, by the terminal, a wireless signal transmitted in thesecond cell, and determining, according to a measurement result of themeasuring, that the second cell is available includes measuring, by theterminal according to the frequency information of the second cell thatis included in the measurement configuration message, the wirelesssignal transmitted in the second cell, and when the measurement resultof the measuring meets the decision condition, determining that thesecond cell is available.

Optionally, before the measuring, by the terminal, a wireless signaltransmitted in the second cell, the method further includes: receiving,by the terminal, a first indication message sent by the second basestation or the first base station, and determining, by the terminalaccording to the first indication message, that the second cell may beadded as a cell communicating with the terminal, where the firstindication message is used to indicate that the second cell may providecommunication for a same terminal together with the first cell.

Optionally, the first base station is a macro base station or a smallnode, or the first base station includes a first node of the first celland a first control node configured to control the first node. The firstnode is configured to process transmission between the terminal and thefirst control node.

The second base station is a small node, a macro base station, or aWireless Fidelity WiFi access point AP.

For another optional implementation of the method, refer to processingof the terminal 201 in the second cell access solution provided in theembodiments of the present invention, and details are not repeated.

FIG. 21 is a flowchart of a fourth cell access method according to anembodiment of the present invention. As shown in FIG. 21, the methodincludes the following steps.

S2101. A first base station of a first cell receives a terminal accessindication message that is sent by a second base station of a secondcell and is used to indicate that a terminal communicating with thefirst cell accesses the second cell.

S2102. After receiving the terminal access indication message, and ifdetermining that the second base station allows addition of the secondcell as a cell communicating with the terminal, the first base stationsends a reconfiguration message to the terminal, so as to instruct theterminal to reconfigure, according to the reconfiguration message, awireless connection established when the terminal accesses the secondcell, and communicate with the second cell by using the configuredwireless connection.

Optionally, the terminal access indication message is further used toindicate that the second base station allows addition of the second cellas a cell communicating with the terminal.

The determining, by the first base station, that the second base stationallows addition of the second cell as a cell communicating with theterminal includes after receiving the terminal access indicationmessage, determining, by the first base station, that the second basestation allows addition of the second cell as a cell communicating withthe terminal.

Optionally, the terminal access indication message carries a wirelessconnection parameter that is used to reconfigure the wirelessconnection.

The sending, by the first base station, a reconfiguration message to theterminal includes adding, by the first base station to thereconfiguration message, the wireless connection parameter obtained fromthe terminal access indication message, and sending the reconfigurationmessage to the terminal.

The reconfiguration message is specifically used to instruct theterminal to reconfigure the wireless connection according to thewireless connection parameter, and communicate with the second cell byusing the configured wireless connection.

Optionally, after the first base station receives the terminal accessindication message, the method further includes sending, by the firstbase station, a cell addition request message to the second basestation, so as to request the second base station to add the second cellas a cell communicating with the terminal.

The determining, by the first base station, that the second base stationallows addition of the second cell as a cell communicating with theterminal includes after receiving a cell addition requestacknowledgement message sent by the second base station in response tothe cell addition request message, determining, by the first basestation, that the second base station allows addition of the second cellas a cell communicating with the terminal.

Optionally, the cell addition request acknowledgement message carries awireless connection parameter that is used to reconfigure the wirelessconnection.

The sending, by the first base station, a reconfiguration message to theterminal includes adding, by the first base station to thereconfiguration message, the wireless connection parameter obtained fromthe cell addition request acknowledgement message, and sending thereconfiguration message to the terminal.

The reconfiguration message is specifically used to instruct theterminal to reconfigure the wireless connection according to thewireless connection parameter, and communicate with the second cell byusing the configured wireless connection.

Optionally, after the first base station sends the reconfigurationmessage to the terminal, the method further includes receiving, by thefirst base station, a reconfiguration complete message sent by theterminal in response to the reconfiguration message, determining, by thefirst base station according to the reconfiguration complete message,that the terminal has completed reconfiguration of the wirelessconnection according to the reconfiguration message, and sending, by thefirst base station, a cell addition complete message to the second basestation, so as to indicate the second base station that the terminal hascompleted reconfiguration of the wireless connection.

Optionally, before the first base station receives the terminal accessindication message, the method further includes sending, by the firstbase station, a measurement configuration message to the terminal, wherethe measurement configuration message includes cell identity informationof the second cell, and information about a decision condition used todetermine whether the second cell is available, so as to instruct theterminal to measure, according to the cell identity information of thesecond cell that is included in the measurement configuration message, awireless signal transmitted in the second cell, and when a measurementresult of the measuring meets the decision condition, determine that thesecond cell is available.

Optionally, before the first base station receives the terminal accessindication message, the method further includes: sending, by the firstbase station, a measurement configuration message to the terminal, wherethe measurement configuration message includes frequency information ofthe second cell, and information about a decision condition used todetermine whether the second cell is available, so as to instruct theterminal to measure, according to the frequency information of thesecond cell that is included in the measurement configuration message, awireless signal transmitted in the second cell, and when a measurementresult of the measuring meets the decision condition, determine that thesecond cell is available.

Optionally, before the first base station sends the measurementconfiguration message, the method further includes sending, by the firstbase station, a first indication message to the terminal, where thefirst indication message is used to indicate that the second cell mayprovide communication for a same terminal together with the first cell.

Optionally, the first base station is a macro base station or a smallnode, or the first base station includes a first node of the first celland a first control node configured to control the first node. The firstnode is configured to process transmission between the terminal and thefirst control node.

The second base station is a small node, a macro base station, or aWireless Fidelity WiFi access point AP.

For another optional implementation of the method, refer to processingof the first base station 202 in the second cell access solutionprovided in the embodiment of the present invention, and details are notrepeated.

FIG. 22 is a flowchart of a fifth cell access method according to anembodiment of the present invention. As shown in FIG. 22, the methodincludes the following steps.

S2201. A second base station of a second cell establishes a wirelessconnection between a terminal and the second cell in a connectionestablishment process initiated by the terminal, and allows the terminalto access the second cell by using the wireless connection.

S2202. After the terminal accesses the second cell, the second basestation sends a terminal access indication message to a first basestation of a first cell communicating with the terminal, so as toindicate that the second cell needs to be added, for the terminal, as acell communicating with the terminal.

Optionally, the terminal access indication message is further used toindicate that the second base station allows addition of the second cellas a cell communicating with the terminal.

The sending, by the second base station, the terminal access indicationmessage to the first base station includes: adding, by the second basestation to the terminal access indication message, a wireless connectionparameter that is used to reconfigure the wireless connection, so as toinstruct the first base station to instruct the terminal to reconfigurethe wireless connection according to the wireless connection parameter.

Optionally, after the second base station sends the terminal accessindication message to the first base station, the method furtherincludes receiving, by the second base station, a cell addition completemessage sent by the first base station, and after receiving the celladdition complete message, communicating, by the second base station,with the terminal by using the reconfigured wireless connection.

Optionally, after the second base station sends the terminal accessindication message to the first base station, the method furtherincludes receiving, by the second base station, a cell addition requestmessage sent by the first base station, where the cell addition requestmessage is used to request the second base station to add the secondcell as a cell communicating with the terminal, and sending, by thesecond base station, a cell addition request acknowledgement message tothe first base station in response to the cell addition request message,so as to indicate that the second base station allows addition of thesecond cell as a cell communicating with the terminal, where the celladdition request acknowledgement message carries a wireless connectionparameter that is used to reconfigure the wireless connection, so as toinstruct the first base station to instruct the terminal to reconfigurethe wireless connection according to the wireless connection parameter.

Optionally, after the second base station sends the cell additionrequest acknowledgement message to the first base station, the methodfurther includes receiving, by the second base station, a cell additioncomplete message sent by the first base station, and after receiving thecell addition complete message, communicating, by the second basestation, with the terminal by using the reconfigured wirelessconnection.

Optionally, before the second base station establishes the wirelessconnection between the terminal and the second cell, the method furtherincludes sending, by the second base station, a first indication messageto the terminal, so as to indicate that the second cell may providecommunication for a same terminal together with the first cell.

The connection establishment process initiated by the terminal isinitiated by the terminal after the terminal receives the firstindication message and determines, according to the first indicationmessage, that the first cell may provide communication for the terminaltogether with the first cell.

Optionally, the first base station is a macro base station or a smallnode, or the first base station includes a first node of the first celland a first control node configured to control the first node. The firstnode is configured to process transmission between the terminal and thefirst control node.

The second base station is a small node, a macro base station, or aWireless Fidelity WiFi access point AP.

For another optional implementation of the method, refer to processingof the second base station 203 in the second cell access solutionprovided in the embodiments of the present invention, and details arenot repeated.

FIG. 23 is a schematic structural diagram of a fifth terminal accordingto an embodiment of the present invention. As shown in FIG. 23, theterminal includes a processing module 2302 and a transceiver module2301.

The processing module 2302 is configured to control the transceivermodule 2301 to report an address of the terminal to a location server.

The transceiver module 2301 is configured to receive an InternetProtocol IP packet sent by an application server in an Internetaccording to the address of the terminal.

The application server obtains the address of the terminal from thelocation server, and the location server is configured to store theaddress of the terminal, and provide the address of the terminal for theapplication server.

Optionally, the processing module 2302 is specifically configured tocontrol the transceiver module 2301 to report the address of theterminal by using control plane signaling.

Optionally, if multiple data transmission paths exist between theterminal and the application server, the processing module 2302 isspecifically configured to for each of the data transmission paths,control the transceiver module 2301 to report an address of the terminalon the path by using the control plane signaling.

Optionally, the address of the terminal includes at least one of thefollowing addresses: a public Internet Protocol IP address of theterminal, an IP address of an access gateway to which the terminal isconnected, or an identity of an access gateway to which the terminal isconnected.

The terminal accesses the Internet by using the access gateway to whichthe terminal is connected, and performs packet transmission with theapplication server in the Internet.

Optionally, the processing module 2302 is specifically configured tocontrol the transceiver module 2301 to send an Internet Protocol IPpacket to the location server, use a source IP address in the sent IPpacket as the address of the terminal, and report the address of theterminal to the location server.

Optionally, if multiple data transmission paths exist between theterminal and the application server, the processing module 2302 isspecifically configured to for each of the multiple data transmissionpaths, control the transceiver module 2301 to send an Internet ProtocolIP packet to the location server by using the data transmission path,use a source IP address in the sent IP packet as an address of theterminal on the data transmission path, and report the address of theterminal to the location server.

Optionally, the location server is a server that is in the Internet andthat is independent of the application server, or the location server islocated in the application server.

Optionally, the processing module 2302 is specifically configured tocontrol the transceiver module 2301 to periodically report the addressof the terminal to the location server, and/or control the transceivermodule 2301 to report the address of the terminal to the location serverwhen a path from the terminal to the application server or the locationserver changes.

Optionally, the processing module 2302 is further configured to beforecontrolling the transceiver module 2301 to report the address of theterminal to the location server, select a to-be-accessed networkaccording to at least one of the following factors: a service type of aservice to be established by the terminal, a quality of service QoSrequirement of a service to be established by the terminal, or a presetnetwork to be preferably accessed by the terminal.

The processing module 2302 is specifically configured to control thetransceiver module 2301 to report, to the location server, an address ofthe terminal in each to-be-accessed network selected by the terminal.

For another optional implementation of the terminal, refer toimplementation of the terminal in the data transmission solutionprovided in the embodiments of the present invention, and details arenot repeated.

FIG. 24 is a schematic structural diagram of a sixth terminal accordingto an embodiment of the present invention. As shown in FIG. 24, theterminal includes a processor 2402 and a transceiver 2401.

The processor 2402 is configured to control the transceiver 2401 toreport an address of the terminal to a location server.

The transceiver 2401 is configured to receive an Internet Protocol IPpacket sent by an application server in an Internet according to theaddress of the terminal.

The application server obtains the address of the terminal from thelocation server, and the location server is configured to store theaddress of the terminal, and provide the address of the terminal for theapplication server.

Optionally, the terminal may be implemented by using a bus architectureshown in FIG. 24. In FIG. 24, the bus architecture may include anyquantity of interconnected buses and bridges, and specifically linkvarious circuits of one or more processors represented by the processor2402 and a memory. The bus architecture may further link various othercircuits such as a peripheral device, a voltage regulator, and a powermanagement circuit. This is well known in the art, and therefore, is notfurther described in this specification. A bus interface provides aninterface. The transceiver 2401 may be multiple elements, that is, mayinclude a transmitter and a receiver, and provide units forcommunicating with various other apparatuses on a transmission medium.For different user equipments, a user interface may be an interface thatcan be externally or internally connected to a required device. Theconnected device includes but is not limited to a keypad, a display, aloudspeaker, a microphone, and a joystick.

Optionally, the terminal may be implemented without using a busarchitecture. For example, the processor 2402 and the transceiver 2401are directly connected to each other, and do not communicate with eachother by using a bus.

For another optional implementation of the processor 2402, refer to theprocessing module 2302. For another optional implementation of thetransceiver 2401, refer to the transceiver module 2301. For anotheroptional implementation of the terminal, refer to implementation of theterminal in the data transmission solution provided in the embodimentsof the present invention, and details are not repeated.

FIG. 25 is a schematic structural diagram of a first location serveraccording to an embodiment of the present invention. As shown in FIG.25, the location server includes a transceiver module 2501, configuredto receive an address of a terminal that is reported by the terminal,and a processing module 2502, configured to notify, an applicationserver performing data transmission with the terminal, of the address ofthe terminal that is received by the transceiver module 2501, so thatthe application server sends an Internet Protocol IP packet to theterminal according to the address of the terminal.

Optionally, the processing module 2502 is specifically configured toafter receiving, by using the transceiver module 2501, a request messagethat is sent by the application server and is for requesting the addressof the terminal, notify, the application server performing datatransmission with the terminal, of the address of the terminal that isreceived by the transceiver module 2501.

Optionally, the transceiver module 2501 is specifically configured toreceive the address of the terminal that is reported by the terminal byusing control plane signaling.

Optionally, the transceiver module 2501 is specifically configured toreceive an address that is of the terminal on each of multiple datatransmission paths existing between the terminal and the applicationserver and that is reported by the terminal for the path by using thecontrol plane signaling.

Optionally, the address of the terminal includes at least one of thefollowing addresses: a public Internet Protocol IP address of theterminal, an IP address of an access gateway to which the terminal isconnected, or an identity of an access gateway to which the terminal isconnected.

The terminal accesses an Internet by using the access gateway to whichthe terminal is connected, and performs packet transmission with theapplication server in the Internet.

Optionally, the transceiver module 2501 is specifically configured toreceive an IP packet sent by the terminal, and use a source IP addressin the received IP packet as the address of the terminal.

Optionally, the transceiver module 2501 is specifically configured toreceive an IP packet sent by the terminal by using each of multiple datatransmission paths existing between the terminal and the applicationserver, and use a source IP address in the received IP packet as anaddress of the terminal on the data transmission path.

Optionally, the location server is a server that is in the Internet andthat is independent of the application server, or the location server islocated in the application server.

Optionally, the transceiver module 2501 is specifically configured toreceive the address of the terminal that is periodically reported by theterminal, and/or receive the address of the terminal that is reported bythe terminal when a path from the terminal to the application server orthe location server changes.

For another optional implementation of the location server, refer to thelocation server in the data transmission solution provided in theembodiments of the present invention, and details are not repeated.

FIG. 26 is a schematic structural diagram of a second location serveraccording to an embodiment of the present invention. As shown in FIG.26, the location server includes a transceiver 2601, configured toreceive an address of a terminal that is reported by the terminal, and aprocessor 2602, configured to notify, an application server performingdata transmission with the terminal, of the address of the terminal thatis received by the transceiver 2601, so that the application serversends an Internet Protocol IP packet to the terminal according to theaddress of the terminal.

Optionally, the location server may be implemented by using a busarchitecture shown in FIG. 26. In FIG. 26, the bus architecture mayinclude any quantity of interconnected buses and bridges, andspecifically link various circuits of one or more processors representedby the processor 2602 and a memory. The bus architecture may furtherlink various other circuits such as a peripheral device, a voltageregulator, and a power management circuit. This is well known in theart, and therefore, is not further described in this specification. Abus interface provides an interface. The transceiver 2601 may bemultiple elements, that is, may include a transmitter and a receiver,and provide units for communicating with various other apparatuses on atransmission medium. For different user equipments, a user interface maybe an interface that can be externally or internally connected to arequired device. The connected device includes but is not limited to akeypad, a display, a loudspeaker, a microphone, and a joystick.

Optionally, the location server may be implemented without using a busarchitecture. For example, the processor 2602 and the transceiver 2601are directly connected to each other, and do not communicate with eachother by using a bus.

For another optional implementation of the transceiver 2601, refer tothe transceiver module 2501. For another optional implementation of theprocessor 2602, refer to the processing module 2502. For anotheroptional implementation of the location server, refer to the locationserver in the data transmission solution provided in the embodiments ofthe present invention, and details are not repeated.

FIG. 27 is a flowchart of a first data transmission method according toan embodiment of the present invention. As shown in FIG. 27, the methodincludes the following steps.

S2701. A terminal reports an address of the terminal to a locationserver.

S2702. The terminal receives an Internet Protocol IP packet sent by anapplication server in an Internet according to the address of theterminal, where the application server obtains the address of theterminal from the location server, and the location server is configuredto store the address of the terminal, and provide the address of theterminal for the application server.

Optionally, the reporting, by a terminal, an address of the terminal toa location server includes reporting, by the terminal, the address ofthe terminal by using control plane signaling.

Optionally, if multiple data transmission paths exist between theterminal and the application server, the reporting, by the terminal, theaddress of the terminal by using control plane signaling includes foreach of the data transmission paths, reporting, by the terminal, anaddress of the terminal on the path by using the control planesignaling.

Optionally, the address of the terminal includes at least one of thefollowing addresses: a public Internet Protocol IP address of theterminal, an IP address of an access gateway to which the terminal isconnected, or an identity of an access gateway to which the terminal isconnected.

The terminal accesses the Internet by using the access gateway to whichthe terminal is connected, and performs packet transmission with theapplication server in the Internet.

Optionally, the reporting, by a terminal, an address of the terminal toa location server includes sending, by the terminal, an InternetProtocol IP packet to the location server, using a source IP address inthe sent IP packet as the address of the terminal, and reporting theaddress of the terminal to the location server.

Optionally, if multiple data transmission paths exist between theterminal and the application server, the reporting, by a terminal, anaddress of the terminal to a location server includes for each of themultiple data transmission paths, sending, by the terminal, an InternetProtocol IP packet to the location server by using the data transmissionpath, using a source IP address in the sent IP packet as an address ofthe terminal on the data transmission path, and reporting the address ofthe terminal to the location server.

Optionally, the location server is a server that is in the Internet andthat is independent of the application server, or the location server islocated in the application server.

Optionally, the reporting, by a terminal, an address of the terminal toa location server includes: periodically reporting, by the terminal, theaddress of the terminal to the location server, and/or reporting, by theterminal, the address of the terminal to the location server when a pathfrom the terminal to the application server or the location serverchanges.

Optionally, before the reporting, by a terminal, an address of theterminal to a location server, the method further includes: selecting,by the terminal, a to-be-accessed network according to at least one ofthe following factors a service type of a service to be established bythe terminal, a quality of service QoS requirement of a service to beestablished by the terminal, or a preset network to be preferablyaccessed by the terminal.

The reporting, by a terminal, an address of the terminal to a locationserver includes reporting, by the terminal to the location server, anaddress of the terminal in each to-be-accessed network selected by theterminal.

For another optional implementation of the method, refer to processingof the terminal in the data transmission solution provided in theembodiments of the present invention, and details are not repeated.

FIG. 28 is a flowchart of a second data transmission method according toan embodiment of the present invention. As shown in FIG. 28, the methodincludes the following steps.

S2801. A location server receives an address of a terminal that isreported by the terminal.

S2802. The location server notifies, an application server performingdata transmission with the terminal, of the received address of theterminal, so that the application server sends an Internet Protocol IPpacket to the terminal according to the address of the terminal.

Optionally, the notifying, by the location server, an application serverperforming data transmission with the terminal, of the received addressof the terminal includes after receiving a request message that is sentby the application server and is for requesting the address of theterminal, notifying, by the location server, the application serverperforming data transmission with the terminal, of the received addressof the terminal.

Optionally, the receiving, by a location server, an address of aterminal that is reported by the terminal includes receiving, by thelocation server, the address of the terminal that is reported by theterminal by using control plane signaling.

Optionally, the receiving, by the location server, the address of theterminal that is reported by the terminal by using control planesignaling includes receiving, by the location server, an address that isof the terminal on each of multiple data transmission paths existingbetween the terminal and the application server and that is reported bythe terminal for the path by using the control plane signaling.

Optionally, the address of the terminal includes at least one of thefollowing addresses: a public Internet Protocol IP address of theterminal, an IP address of an access gateway to which the terminal isconnected, or an identity of an access gateway to which the terminal isconnected.

The terminal accesses an Internet by using the access gateway to whichthe terminal is connected, and performs packet transmission with theapplication server in the Internet.

Optionally, the receiving, by a location server, an address of aterminal that is reported by the terminal includes receiving, by thelocation server, an IP packet sent by the terminal, and using a sourceIP address in the received IP packet as the address of the terminal.

Optionally, the receiving, by the location server, an IP packet sent bythe terminal, and using a source IP address in the received IP packet asthe address of the terminal includes receiving, by the location server,an IP packet sent by the terminal by using each of multiple datatransmission paths existing between the terminal and the applicationserver, and using a source IP address in the received IP packet as anaddress of the terminal on the data transmission path.

Optionally, the location server is a server that is in the Internet andthat is independent of the application server, or the location server islocated in the application server.

Optionally, the receiving, by a location server, an address of aterminal that is reported by the terminal includes receiving, by thelocation server, the address of the terminal that is periodicallyreported by the terminal, and/or receiving, by the location server, theaddress of the terminal that is reported by the terminal when a pathfrom the terminal to the application server or the location serverchanges.

For another optional implementation of the method, refer to processingof the location server in the data transmission solution provided in theembodiments of the present invention, and details are not repeated.

In conclusion, in the embodiments of the present invention, a terminalautonomously selects a to-be-accessed second cell, and actively requestsa first base station to add a second cell. Compared with a solution thatis in a current cell handover procedure and in which a terminal sends ameasurement report and a base station performs handover decision, in theforegoing solution provided in the embodiments of the present invention,partial processing is performed by the terminal, so that processing of anetwork device such as a base station can be reduced, and implementationcomplexity of the network device can be reduced.

Further, a terminal may first access a second cell, and a second basestation of the second cell notifies a first base station of the accessof the terminal. In this optional solution, the terminal can alsoautonomously select a to-be-accessed second cell.

Still further, a terminal reports an address of the terminal to alocation server. The location server sends the received address of theterminal to an application server performing data transmission with theterminal, or an application server obtains the address of the terminalfrom the location server. The application server sends an IP packet tothe terminal according to the obtained address of the terminal. Theapplication server obtains the address of the terminal from the locationserver, so that the application server can send an IP packet to theterminal according to the obtained address of the terminal.

Persons skilled in the art should understand that the embodiments of thepresent invention may be provided as a method, a system, or a computerprogram product. Therefore, the present invention may use a form ofhardware only embodiments, software only embodiments, or embodimentswith a combination of software and hardware. Moreover, the presentinvention may use a form of a computer program product that isimplemented on one or more computer-usable storage media (including butnot limited to a disk memory, a CD-ROM, or an optical memory) thatinclude computer-usable program code.

The present invention is described with reference to the flowchartsand/or block diagrams of the method, the device (system), and thecomputer program product according to the embodiments of the presentinvention. It should be understood that computer program instructionsmay be used to implement each process and/or each block in theflowcharts and/or the block diagrams and a combination of a processand/or a block in the flowcharts and/or the block diagrams. Thesecomputer program instructions may be provided for a general-purposecomputer, a dedicated computer, an embedded processor, or a processor ofany other programmable data processing device to generate a machine, sothat the instructions executed by a computer or a processor of any otherprogrammable data processing device generate an apparatus forimplementing a specific function in one or more processes in theflowcharts and/or in one or more blocks in the block diagrams.

These computer program instructions may be stored in a computer readablememory that can instruct the computer or any other programmable dataprocessing device to work in a specific manner, so that the instructionsstored in the computer readable memory generate an artifact thatincludes an instruction apparatus. The instruction apparatus implementsa specific function in one or more processes in the flowcharts and/or inone or more blocks in the block diagrams.

These computer program instructions may be loaded onto a computer oranother programmable data processing device, so that a series ofoperations and steps are performed on the computer or the anotherprogrammable device, thereby generating computer-implemented processing.Therefore, the instructions executed on the computer or the anotherprogrammable device provide steps for implementing a specific functionin one or more processes in the flowcharts and/or in one or more blocksin the block diagrams.

Although some preferred embodiments of the present invention have beendescribed, persons skilled in the art can make changes and modificationsto these embodiments once they learn the basic inventive concept.Therefore, the following claims are intended to be construed as to coverthe preferred embodiments and all changes and modifications fallingwithin the scope of the present invention.

Obviously, persons skilled in the art can make various modifications andvariations to the present invention without departing from the spiritand scope of the present invention. The present invention is intended tocover these modifications and variations provided that they fall withinthe scope of protection defined by the following claims and theirequivalent technologies.

What is claimed is:
 1. A terminal comprising: an interface circuit; aprocessor; and a non-transitory computer readable medium having aprogram stored thereon for execution by the processor, the programhaving instructions to: establish a first wireless connection with afirst base station of a first cell; determine to communicate with asecond cell; establish a second wireless connection with a second basestation of the second cell, the establishing the second wirelessconnection causing the second base station to send a terminal accessindication message to the first base station; access the second cell onthe second wireless connection; receive, through the interface circuitand from the first base station, a reconfiguration message in responseto the terminal having accessed the second cell, and indicating that thesecond base station has allowed addition of the second cell as a cellcommunicating with the terminal; reconfigure the second wirelessconnection according to the reconfiguration message; and communicatewith the second cell on the reconfigured second wireless connection. 2.The terminal according to claim 1, wherein the program further includesinstructions to send, through the interface circuit, after reconfiguringthe second wireless connection according to the reconfiguration message,and before communicating with the second cell on the reconfigured secondwireless connection, a reconfiguration complete message to the firstbase station indicating that the terminal has completed reconfigurationof the second wireless connection according to the reconfigurationmessage.
 3. The terminal according to claim 1, wherein the instructionsto determine to communicate with the second cell include instructionsto: measure a wireless signal transmitted in the second cell beforeestablishing the second wireless connection to the second cell; anddetermine, according to a measurement result of the measuring, that thesecond cell is available.
 4. The terminal according to claim 3, whereinthe program further includes instructions to receive, through theinterface circuit and from the first base station, before the wirelesssignal transmitted in the second cell is measured, a measurementconfiguration message comprising cell identity information of the secondcell and information about a decision condition used to determinewhether the second cell is available; wherein the instructions tomeasure the wireless signal transmitted in the second cell includeinstructions to measure the wireless signal transmitted in the secondcell according to the cell identity information of the measurementconfiguration message; and wherein the instructions to determine thatthe second cell is available include instructions to determine that thesecond cell is available in response to the measurement result of thewireless signal transmitted in the second cell meeting the decisioncondition.
 5. The terminal according to claim 3, wherein the programfurther includes instructions to receive, through the interface circuitfrom the first base station, before the wireless signal transmitted inthe second cell is measured, a measurement configuration messagecomprising frequency information of the second cell and informationabout a decision condition used to determine whether the second cell isavailable; wherein the instructions to measure the wireless signaltransmitted in the second cell include instructions to measure thewireless signal transmitted in the second cell according to thefrequency information of the measurement configuration message; andwherein the instructions to determine that the second cell is availableinclude instructions to determine that the second cell is available inresponse to the measurement result of the wireless signal transmitted inthe second cell meeting the decision condition.
 6. The terminalaccording to claim 3, wherein the program further includes instructionsto: receive, through the interface circuit, before the wireless signaltransmitted in the second cell is measured, a first indication messagesent by one of the first base station or the second base station; anddetermine, according to the first indication message, that the secondcell is permitted to be added as a cell communicating with the terminal,wherein the first indication message indicates that the second cell isto provide communication for a same terminal together with the firstcell.
 7. The terminal according to claim 1, wherein the first basestation comprises at least one of an evolved NodeB (eNodeB), a NodeB, abase transceiver station (BTS), an access point (AP), and an accesscontroller (AC).
 8. A method, comprising: establishing, by a terminal, afirst wireless connection with a first base station of a first cell;determining, by the terminal in communication with the first cell, tocommunicate with a second cell; establishing a second wirelessconnection with a second base station of the second cell, theestablishing the second wireless connection causing the second basestation to send a terminal access indication message to the first basestation; accessing, by the terminal, the second cell on the secondwireless connection; receiving, by the terminal from the first basestation, a reconfiguration message in response to the terminal havingaccessed the second cell, and indicating that the second base stationhas allowed addition of the second cell as a cell communicating with theterminal; reconfiguring the second wireless connection according to thereconfiguration message; and communicating with the second cell on thereconfigured second wireless connection.
 9. The method according toclaim 8, further comprising sending, by the terminal, afterreconfiguring the second wireless connection according to thereconfiguration message, and before communicating with the second cellon the reconfigured second wireless connection, a reconfigurationcomplete message to the first base station indicating that the terminalhas completed reconfiguration of the second wireless connectionaccording to the reconfiguration message.
 10. The method according toclaim 8, wherein determining to communicate with the second cellcomprises: measuring, by the terminal, a wireless signal transmitted inthe second cell before establishing the second wireless connection tothe second cell; and determining, according to a measurement result ofthe measuring the wireless signal, that the second cell is available.11. The method according to claim 10, further comprising receiving, bythe terminal from the first base station, before the wireless signaltransmitted in the second cell is measured, a measurement configurationmessage comprising cell identity information of the second cell andinformation about a decision condition used to determine whether thesecond cell is available; wherein measuring the wireless signaltransmitted in the second cell comprises measuring the wireless signaltransmitted in the second cell according to the cell identityinformation of the measurement configuration message; and wherein thedetermining that the second cell is available comprises determining thatthe second cell is available in response to the measurement result ofthe wireless signal transmitted in the second cell meeting the decisioncondition.
 12. The method according to claim 10, further comprisingreceiving, by the terminal from the first base station, before thewireless signal transmitted in the second cell is measured, ameasurement configuration message comprising frequency information ofthe second cell and information about a decision condition used todetermine whether the second cell is available; and wherein themeasuring the wireless signal transmitted in the second cell comprisesmeasuring the wireless signal transmitted in the second cell accordingto the frequency information of the measurement configuration message;and wherein determining that the second cell is available comprisesdetermining that the second cell is available in response to themeasurement result of the wireless signal transmitted in the second cellmeeting the decision condition.
 13. The method according to claim 10,further comprising: receiving, by the terminal, before the wirelesssignal transmitted in the second cell is measured, a first indicationmessage sent by one of the first base station or the second basestation; and determining, according to the first indication message,that the second cell is permitted to be added as a cell communicatingwith the terminal, wherein the first indication message indicates thatthe second cell is to provide communication for a same terminal togetherwith the first cell.
 14. The method according to claim 8, wherein thefirst base station comprises at least one of an evolved NodeB (eNodeB),a NodeB, a base transceiver station (BTS), an access point (AP), and anaccess controller (AC).
 15. A base station, comprising: a processor; anda non-transitory computer readable medium having a program storedthereon for execution by the processor, the program having instructionsto: communicating with a terminal in a first cell; receiving, from asecond base station of a second cell, a terminal access indicationmessage indicating that the terminal has accessed the second cell;sending, to the second base station, a cell addition request message;receiving, from the second base station, an acknowledgement messageindicating that the second base station has allowed addition of thesecond cell as a cell communicating with the terminal; and sending, tothe terminal, a reconfiguration message in response to the terminalhaving accessed the second cell, and indicating the second base stationhas allowed addition of the second cell as the cell communicating withthe terminal, wherein sending the reconfiguration message causes theterminal to reconfigure a wireless connection according to thereconfiguration message and communicate with the second cell on thereconfigured wireless connection.
 16. The base station according toclaim 15, wherein the program further includes instructions to receive,from the terminal, a reconfiguration complete message indicating thatthe terminal has completed reconfiguration of the wireless connectionaccording to the reconfiguration message.
 17. The base station accordingto claim 15, wherein the program further includes instructions to send,to the terminal, a measurement configuration message, causing theterminal to measure a wireless signal transmitted in the second cellbefore establishing the wireless connection to the second cell, andfurther causing the terminal to determine, according to a measurementresult of the measuring, that the second cell is available.
 18. The basestation according to claim 17, wherein the measurement configurationmessage comprises cell identity information of the second cell andinformation about a decision condition used by the terminal to determinewhether the second cell is available; and wherein sending themeasurement configuration message causes the terminal to measure thewireless signal transmitted in the second cell according to the cellidentity information of the measurement configuration message, andfurther causes the terminal to determine that the second cell isavailable in based on the measurement result of the wireless signaltransmitted in the second cell having met the decision condition. 19.The base station according to claim 17, wherein the measurementconfiguration message comprises frequency information of the second celland information about a decision condition used to determine whether thesecond cell is available; and wherein sending the measurementconfiguration message causes the terminal to measure the wireless signaltransmitted in the second cell according to the frequency information ofthe measurement configuration message, and further causes the terminalto determine that the second cell is available based on the measurementresult of the wireless signal transmitted in the second cell having metthe decision condition.
 20. The base station according to claim 17,wherein the program further includes instructions to: send, to theterminal, before the wireless signal transmitted in the second cell ismeasured, a first indication message causing the terminal to determine,according to the first indication message, that the second cell ispermitted to be added as a cell communicating with the terminal, whereinthe first indication message indicates that the second cell is toprovide communication for a same terminal together with the first cell.